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Mandatory Experiments Booklet Procedure and Results Table

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Mandatory Experiments Booklet Procedure and Results Table

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Handy to print for each group for collecting data during the experiments or use as summary revision sheets.

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Online exam questions year by year or topic by topic

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Are you a Junior or Leaving Cert student looking to ace your exams? Or a teacher looking to make your students exam ready? Look no further!

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MS Forms; To measure the specific latent heat of vaporisation of water

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MS Forms; To measure the specific latent heat of vaporisation of water

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MS Forms; To measure the specific latent heat of fusion of ice

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MS Forms; To measure the specific latent heat of fusion of ice

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MS Forms; To measure the specific heat capacity of a substance (by mechanical or electrical means)

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MS Forms; To measure the specific heat capacity of a substance (by mechanical or electrical means)

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MS Forms; To establish the calibration curve of a thermometer

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MS Forms; To establish the calibration curve of a thermometer

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MS Forms; To measure the variation of the fundamental frequency of a stretched string with tension.

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MS Forms; To measure the variation of the fundamental frequency of a stretched string with tension.

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MS Forms; To measure the variation of the fundamental frequency of a stretched string with tension.

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MS Forms; To measure the variation of the fundamental frequency of a stretched string with tension.

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MS Forms; To measure the speed of sound in air

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MS Forms; To measure the speed of sound in air

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MS Forms; To measure the wavelength of monochromatic light

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MS Forms; To measure the wavelength of monochromatic light

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MS Forms; To measure the refractive index of a substance (Liquid)

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MS Forms; To measure the refractive index of a substance (Liquid)

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To Measure the Refractive Index of a Substance

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MS Forms; Focal length of a converging lens

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MS Forms; Focal length of a converging lens

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MS Forms; Focal length of concave mirror

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MS Forms; Focal length of concave mirror

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Voltage/Potential Difference

Electricity and Magnetism

Van de Graaff generator safety

Teaching Guidance for 14-16

Van de Graaff generator demonstrations can provide useful insights into electrical phenomena, which are at the same time memorable.

It is essential the Van de Graaff generators for school science are obtained through reputable school science equipment suppliers. The sphere has a capacitance, and will store energy electrostatically as a result of the separation of charge. The energy stored electrostatically by the sphere should not exceed 0.5 J.

Do not add devices to the sphere that increase the capacitance.

Van de Graaff generators with mains powered pulleys must be electrically inspected and tested in the same way as other mains powered equipment.

When carrying out the hair-standing-on-end demonstration, do it with one person at a time. After the demonstration, to avoid a sudden discharge, the person should take their hand off the sphere and touch the surface of a wood bench top (avoiding metal fittings such as gas taps). Alternatively, hand the charged person a wooden metre rule. After a few moments, they will be discharged.

It is not advisable for people to participate in practical work with Van de Graaff generators if they have heart conditions, or a pacemaker, or other electronic medical equipment fitted.

The electrical discharge from a Van de Graaff generator can wreck electronic circuits, so equipment such as computers and instrumentation with electronic circuits should be kept well away.

The Van de Graaff generators designed for schools are usually the triboelectric type; these are the most suitable. The transfer of charge is achieved by a rubber belt driven by a plastic pulley, with an arrangement of metal combs at either end of the belt. Charge is transferred to a metal sphere (a capacitor) and very high voltages are achieved between the sphere and ground, typically in the range 200 kV to 300 kV.

Using a Van de Graaff generator, one is quite likely to receive a short shock by accidental or intentional contact with the charged dome. An enquiry to CLEAPSS has revealed no recorded incident of direct injury caused by shocks from the correct use of school Van de Graaff generators. However, some people are more sensitive than others and can find the shocks very unpleasant and painful. For this reason, only volunteers should take direct part in the practical work.

The shock is a single unidirectional pulse of short duration; a capacitor discharge through the resistance of the body and contacts. Using rough values of sphere capacitance, 10 pF, and body resistance, 1000 ohms, the discharge time through a person will be of the order of nanoseconds and certainly less than a millisecond. The capacitance of the sphere needs to be low enough that at maximum voltage, the energy transferred by the discharge current through the body causes at most no more than an unpleasant or painful sensation. The current flowing and energy transferred to the body should be well below that which could cause any risk of ventricular fibrillation.

For an impulse current I Amps of short duration t seconds ( t < 10 ms) through the body, the principal factor for the initiation of ventricular fibrillation is the value of or (IEC 2007). At high applied voltages, the resistance of the adult body (left hand to right hand) is at least 575 ohms for 95% of the population (IEC 2005). The total body resistance for children is expected to be higher but of the same order of magnitude. The IEC gives a threshold value of 'Specific Fibrillation Energy', for a 1 ms current impulse, of ValueExponent{2}{-3} A 2 s. Below this threshold there is no evidence of fibrillation. The Specific Fibrillation 'Energy' can be regarded as the energy dissipated per unit resistance of the body through which the current flows. Note that 'specific' here means 'per unit resistance' rather than 'per unit mass'.

At 575 ohms and discharge time not exceeding 1 ms, the energy stored electrostatically by the capacitor would need to be at least 1.1 J to reach the Specific Fibrillation Energy. Although this is a very conservative estimate because the discharge time is likely to be much less than 1 ms, Van de Graaff generators that can store more than 1 J of energy electrostatically by the sphere should be avoided. A discharge of 1 J affects everybody severely (BSI 1991).

An estimate of the energy stored electrostatically by the sphere can be made by calculating the sphere capacitance, C = 4 π ε 0 r (where C is in farads, r is the sphere radius in metres and ε 0 is the permittivity of free space), estimating the voltage, V , using the length of spark gap, and calculating the energy E , in joules, from E = 0.5 C V 2.

Generally speaking, sphere diameters of Van de Graaff generators should be about 20 cm or less. Using data from one manufacturer's specification, the sphere diameter is given as 20 cm and the maximum voltage 250 kV, the energy stored electrostatically would be 0.35 J, well below 1 J. If this is compared to a sphere diameter of, say, 25 cm and a maximum voltage of 350 kV, then energy stored electrostatically would be 0.85 J. This would still be below 1 J, but the shocks would be correspondingly more unpleasant and painful, and this may put off some people from using the generator.

If you wish to estimate the voltage across the sphere and ground, you can do this by finding the maximum spark length. Wait until the sphere is fully charged, then bring up a grounded sphere slowly until you obtain a spark discharge. This technique has limitations and you should do it carefully several times to find the maximum spark length. Do the test on a dry day with low relative humidity so the Van de Graaff generator is working at its best.

Note that the rule-of-thumb 3 kV/mm is only a reasonable rule for voltages below 100 kV.

References
IEC 2007. IEC/TS 60479-2:2007. Effects of human beings and livestock - Part 2: Special aspects. IEC 2005. IEC/TS 60479-1:2005. Effects of human beings and livestock - Part 1: General aspects. BSI 2002. BS EN 60052:2002. Voltage measurement by means of standard air gaps. BSI 1991. BS5958-1:1991. Code of practice for control of undesirable static electricity Part 1: General considerations. [Replaced by PD CLC/TR 50404:2003 but remains current.]

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Voltage/Potential Difference Electricity and Magnetism Teaching Guidance for 14-16 Van de Graaff generator demonstrations can provide useful insights into electrical phenomena, which are at the same time memorable. It is essential the Van de Graaff generators for school science are obtained through reputable school science equipment suppliers.

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MS Forms; Measure the acceleration due to gravity using a simple pendulum

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MS Forms; Measure the acceleration due to gravity using a simple pendulum

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MS Forms; Verify the laws of equilibrium for a set of coplanar forces

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MS Forms; Verify the laws of equilibrium for a set of coplanar forces

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MS Forms; Measure acceleration due to gravity by freefall

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MS Forms; Measure acceleration due to gravity by freefall

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MS Forms; Verify the principle of conservation of momentum

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MS Forms; Verify the principle of conservation of momentum

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MS Forms; Force proportional to acceleration

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MS Forms; Force proportional to acceleration

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Semiconductor diode recap video assessment

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Easily create beautiful interactive video lessons for your students you can integrate right into your LMS. Track students' progress with hassle-free analytics as you flip your classroom!

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MS Forms; Variation of current with potential difference of a semiconductor diode.

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MS Forms; Variation of current with potential difference of a semiconductor diode.

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MS Forms; Variation of current with potential difference for copper sulfate solution 

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MS Forms; Variation of current with potential difference for copper sulfate solution 

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MS Forms; Variation of current with potential difference for a filament bulb 

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MS Forms; Variation of current with potential difference for a filament bulb 

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Ms Forms; Variation of current with potential difference for a metallic conductor 

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Ms Forms; Variation of current with potential difference for a metallic conductor 

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Physics Online: How to check your circuits are working

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Physics Online: How to check your circuits are working

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Build your circuits step by step so you know all your components are working.

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A Level Physics - How to make circuits that work every time!

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Good introductory investigations to develop students understanding of circuits before doing the mandatory experiments.

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Excellent lectures by the infamous Walter Lewin. Excellent for supporting your content knowledge for the mandatory experiments.

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Lectures by Walter Lewin. They will make you ♥ Physics.

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This channel contains the complete 8.01x (Physics I: Classical Mechanics), 8.02x (Physics II: Electricity and Magnetism) and 8.03 (Physics III: Vibrations and Waves) lectures as presented by Walter Lewin in the fall of 1999, spring of 2002 and fall of 2004. The 8.01x and 8.02x edX lectures are high resolution (480p) versions of the more commonly seen OCW versions.

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JavaScript seems to be disabled in your browser. For the best experience on our site, be sure to turn on Javascript in your browser. We've got the best and latest right here at Timstar. View all 'Timstar is an outstanding supplier of equipment and chemicals.

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Lennox: Equipment for the mandatory experiments

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Lennox: Equipment for the mandatory experiments

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Great for quickpick lists as a guide for your physics prep room.

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Physics Online: Videos for A Level physics and GCSE

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Physics Online: Videos for A Level physics and GCSE

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Lots of useful videos applicable to the LC syllabus.

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revision "gcse physics" "a level physics" "physics revision" "exam revision" physics

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I want you to love physics as much as I do - and feel confident as you prepare for any exams you have coming up. I'm Lewis Matheson, a former Physics Teacher, now working full-time creating videos and resources to help you understand GCSE and A Level physics.

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Nice short video on circuit components and their symbols.

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@legophysicsguy has an amazing series of videos online and also posts on twitter. One to follow!

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How to use Multimeters - A Level Physics

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Noel Cunningham videos including the mandatory experiments. Noel has a brilliant collection of videos some of which are the mandatory experiments and lots of others to choose from too!

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Nice simulation for Joule's Law. You can pause the simulation when you want to record time and temperature.

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Νόμος του Joule

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Can be used for a very simple circuit to introduce relationship between current and voltage before looking at potential divider circuit. Voltage of battery can be changed by clicking on it.

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‪Circuit Construction Kit: DC - Virtual Lab‬

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MS Forms; Resistance Of Thermistor V Temperature 

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MS Forms; Resistance Of Thermistor V Temperature 

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MS Forms; Resistance of metallic conductor V temperature 

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MS Forms; Resistance of metallic conductor V temperature 

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Science equipment for labs and Data loggers

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Science equipment for labs and Data loggers

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All science lab tender lists can be found here on the Department of Education website.

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Specifications and standards for furniture and equipment for post-primary schools.

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This Department of Education document is used for the tender for new labs. It is useful as a guideline as to what your lab should have.

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Excel spreadsheet for mandatory experiments calculations 

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Excel spreadsheet for mandatory experiments calculations 

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PDST document by James Frawley that allows you to enter data collected and draw graphs. Excellent way of quickly looking for outliers from a students data to display to the whole class. Recently updated to latest version of Excel by Máire Duffy, Ken Forbes and Paul Nugent.

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PhET simulation allowing students to plot a calibration curve of pressure (constant volume) or volume (constant pressure) against temperature.

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Brilliant interactive simulations which allow collecting of data and graph plotting for certain experiments.

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Online Labs for schools - Developed by Amrita Vishwa Vidyapeetham and CDAC Online Lab

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The OLabs is based on the idea that lab experiments can be taught using the Internet, more efficiently and less expensively. The labs can also be made available to students with no access to physical labs or where equipment is not available owing to being scarce or costly.

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Great simulations for physics, chemistry, biology and maths.

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Free interactive science simulation(Virtual lab) written by JavaScript Simulates various natural phenomena Includes about Physics, Chemistry, Earth, Astronomy, Biology, Measurment, Mathmatics... No need to plugin add-ons Available on mobile devices and tablets also Free of charge / No membership About...

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Free interactive science simulation(Virtual lab) written by JavaScript Simulates various natural phenomena Includes about Physics, Chemistry, Earth, Astronomy, Biology, Measurment, Mathmatics... No need to plugin add-ons Available on mobile devices and tablets also Free of charge / No membership About...

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Brilliant interactive simulations.

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oPhysics: Interactive Physics Simulations

Select a simulation from one of the above categories or click on a category to see descriptions of the simulations for that category.

The oPhysics website is a collection of interactive physics simulations. It is a work in progress, and likely always will be. Content will be added as time allows.

All of the content on this site was created by me, Tom Walsh. I retired after teaching high school physics for 27 years, and AP Physics for 25 years. Please click my name above to send me feedback about these simulations or suggestions for new simulations I could create.
Most of the animated illustrations and all of the interactive simulations on this site were created using the wonderful GeoGebra software. GeoGebra is a free program that makes it very easy to create animations and simulations for anyone with a good understanding of math or physics. To browse or search for pre-made math and physics simulations (including those used on this site) and for more information about the software please visit their website: www.geogebra.org.
Please feel free to use any of the content on this site for non-profit educational purposes.

10/2/2022: Added Electron Charge to Mass Ratio Lab (In Electricity and Magnetism).

10/2/2022: Added Image Formation with Convex Lenses (In Light).

10/2/2022: Added Perfect Card Shuffling (In Fun Stuff).

About oPhysics

About The Author

About GeoGebra

Permissions

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oPhysics: Interactive Physics Simulations Select a simulation from one of the above categories or click on a category to see descriptions of the simulations for that category. The oPhysics website is a collection of interactive physics simulations. It is a work in progress, and likely always will be.

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UCC have collated materials for each mandatory experiment.
Excellent website.

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UCC have put together some remote learning resources to help leaving cert students revise for the mandatory leaving cert physics experiments.

A variety of sources have been used to collect the resources below including c4science YouTube Videos, Pasco Scientific Distance Learning Youtube Videos, Simple Science and Maths YouTube Videos, write-ups from the Professional Development Service for Teachers and a variety of online labs and simulations. These resources focus on either the Leaving Cert specifically or on distance learning. The online labs / simulation allow you to explore the concepts in the lab again and should not be considered a replacement for completing the lab in school.

If you have an interest in Physics check out our Undergraduate courses. Studying Physics can lead to a huge range of careers due to the skills and ways of thinking it teaches you. See where some of our own graduates have ended up.

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Leaving Cert Mandatory Experiments | University College Cork

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UCC have put together some remote learning resources to help leaving cert students revise for the mandatory leaving cert physics experiments. A variety of sources have been used to collect the resources below including c4science YouTube Videos, Pasco Scientific Distance Learning Youtube Videos, Simple Science and Maths YouTube Videos, write-ups from the Professional Development Service for Teachers and a variety of online labs and simulations.

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Created by Tom Tierney, Castleknock College. Excellent booklet which can be used by teachers or by students.

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Created by Tom Tierney. Fantastic articles and resources on all aspects of the course.

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Fantastic website full of virtual lab experiments. Free sign-up. There are videos showing how to do the experiment, notes and then the simulator for the investigation.

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Physical Sciences : Amrita Vishwa Vidyapeetham Virtual Lab

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Mechanics, Thermodynamics, Optics, Electricity and Magnetism, Basic Electric Circuits, Modern Physics Virtual Labs...

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Great website full of interactive simulations. Subscription required.

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Summary

The multimeter is an electrical measuring instrument that combines the functions of an ammeter (current measurement), a voltmeter (voltage measurement), and an ohmmeter (measurement of the value of resistance).

This animation simulates the action of various electrical quantities. All configurations can be tested and any resulting connection errors are indicated.

Click on a terminal to draw a wire. Click in the middle of a wire to disconnect it.
Click on a multimeter graduation to move the selector.

Learning goals

To know how to measure voltage, current and resistance with a multimeter.

To understand how to connect a multimeter for each mode of operation.

To understand the role of the graduations in measurement accuracy.

Learn more

To measure electrical quantities with a multimeter, you must:

know the type of measurement (current, voltage, resistance, and AC or DC amplitude)

properly connect the multimeter in the...

Subscribe now to read more about this topic!

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The multimeter is an electrical measuring instrument that combines the functions of an ammeter (current measurement), a voltmeter (voltage measurement), and an ohmmeter (measurement of the value of resistance). This animation simulates the action of various electrical quantities. All configurations can be tested and any resulting connection errors are indicated.

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Brilliant website with loads of really visual simulations. Lots of extra materials available to support the simulations including Word/PDFs created by other teachers.

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By converting our sims to HTML5, we make them seamlessly available across platforms and devices. Whether you have laptops, iPads, chromebooks, or BYOD, your favorite PhET sims are always right at your fingertips.Become part of our mission today, and transform the learning experiences of students everywhere!

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Excellent website full of fun and simple experiments to add to your lessons to help explain concepts and improve understanding.

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Bernard and Barbro Osher Gallery 1: Human Phenomena

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All the LC mandatory physics experiments as simulations. Amazing resource created by Seán Foley, Scoil Mhuire Gan Smál, Blarney

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Because of security issues with Java it has now be re-written using HTML5 and JavaScript.

It has been created to help Leaving Certificate students of Physics and Applied Maths.

The physics section contains simulations of all 24 Leaving Cert. Physics experiments.

The Applied Maths has just a few simulations, I hope to add more when I have time.

I hope you find this site interesting and helpful.

If you have any comments or suggestions I would be happy to hear from you at snfoley (at) gmail.com

Sean Foley, Scoil Mhuire Gan Smál, Blarney (Retired)Physics Experiments Applied Maths

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Because of security issues with Java it has now be re-written using HTML5 and JavaScript. It has been created to help Leaving Certificate students of Physics and Applied Maths. The physics section contains simulations of all 24 Leaving Cert. Physics experiments. The Applied Maths has just a few simulations, I hope to add more when I have time.

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Fantastic for reference and alternative methods for various experiments in A-level physics. Lots of relevant experiments for LC physics for example Boyle's law.

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NUStem video on measuring acceleration due to gravity using four different methods.

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NUStem video on measuring acceleration due to gravity using four different methods.

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A-level specifications from all the exam boards include "measure the acceleration due to gravity of a freely falling body" as one of the practicals. Students might be a bit uninterested in measuring the value of a constant with which they are already familiar. However, this practical is likely to be undertaken close to the beginning of an A level course. As such, it can be used to make a number of valuable points, each of which is worth introducing our students to at this stage:

By comparing more than one method, students can practice thinking critically about experimental methods.

Learn to assess and reduce uncertainty.

Consider how to present and process data.

Discuss what is meant by 'constant.'

The film shows four different methods of measuring g using a falling object:

Drop a ball and time its fall with a stopwatch.

Drop a 'g-ball', which times its own fall.

Drop a ball through light gates.

Use an electromagnetic switch to release a ball bearing, with triggered timing.

Which of these methods you use might depend on your students' skill, your own preference, apparatus availability, ease of data collection or processing, and class size. It's good to compare at least two methods (even if one is shown as a demonstration only), to prompt and inform discussion about precision, accuracy and uncertainty.

What's not in the film

Since we anticipate this practical being used early in the A level course, we've not included comments about how to do a full error analysis. There's more error handling in some of the other films in the series, and we're planning to complete a film specifically about error as the series continues.

An aside about language

The ASE book The Language of Measurement (£13.50/£8.50 members) refers to precision as:

A measurement is precise if values cluster closely.

In the film, at about 2:22, the word 'precision' is used to mean the timer's smallest scale division. This is us showing our age! A better term might be 'resolution'.

Other ASE definitions:

Accuracy: a result is accurate if it is close to the true value.

Uncertainty: the interval within which the true value can be expected to lie.

Calculating g from h and t

Methods 1, 2 and 4 give values of the time \(t\) for a ball to fall from rest at a height \(h\). From the equation:

\(s = ut + \frac{1}{2}at^2\)

we have:

\(g = \frac{2h}{t^2}\)

Measuring \(t\) for different values of \(h\) allows a graph to be drawn of \(h\) against \(t^2\). The gradient of that graph is \(g/2\).

In method 3 the ball falls through two light gates separated by a distance \(h\). Each gate gives a value for the average speed of the ball as it passes through, so we can use \(v^2 = u^2 + 2as\) to find its acceleration between the gates.

Uncertainties arise in four ways:

Starting the timer.

During the ball's descent, due to air resistance or other factors.

Stopping the timer.

Determining the height of the fall.

Students can think about these as they compare the different methods. They can try to assess whether each uncertainty will make the values of \(t\) and \(h\) too big or too small, or just more uncertain. They can also discuss how each factor will affect the value of \(g\).

For example: if the measured value of \(t\) is too big, the calculated value of \(g\) will be too small, because t is on the bottom line of \(g = 2h/t^2\).

Eventually, students must be able to assess the overall uncertainty in their measurements. For example, they might state their measured value as \(g = 8.7 \pm 1~\mathrm{ms^{-2}}\). For now, however, it is a good start to be able to calculate the percentage error, e.g.:

\(\frac{9.8 - 8.7}{9.8} \times 100\% = 11\%\)

Drop a ball from a measured height \(h\); start and stop a timer to find \(t\).

Students should be able to comment on the problems with starting and stopping the timer at the correct instants. Reaction time here is not the same as the human response to a random stimulus, since we can watch the ball falling and anticipate the correct moment to stop the timer. It's still, however, a poor way to measure \(g\)!

Repeated measurements for a fixed value of \(h\) will give a range of values for \(t\). Some students may be better at using a consistent technique, which will give a smaller spread in the values of \(t\). This reduces the random error, but there may still be systematic error, which itself may be revealed by repeating the experiment for different values of \(h\).

Questions to ask your students:

What's a better way to release the ball?

What's a better way to measure the time?

Why don't we try to reduce the uncertainty in measuring \(h\)?

These cost about £20 + VAT from education suppliers, one of which is Timstar.

The g-ball starts timing when released and stops timing as soon as it hits the floor. Like most stopclocks, it measures to a resolution of 0.01 seconds. The switch release can limit accuracy, but overall the g-ball is a quick way to collect a large number of data points. In the film, Alom and Christina use an L-shaped bracket clipped to a metre rule to press the release switch, to aid a clean release.

Questions to ask your students:

How is this better than using a stopwatch?

How can they 'average' their data?

Your students could just repeatedly drop the g-ball from the same height and average all their data, then substitute their average \(t\) into \(s = \frac{1}{2}gt^2\) to find \(g\). Much better would be to exclude anomalous values first, and better still would be to plot a graph of \(h\) against \(t^2\) to spot those anomalies.

If you're going to plot a graph, however, you might as well have two meaningful variables. In the film, Christina and Alom drop the ball from different heights and collect a lot of (not very good!) data quickly.

This approach:

Helps to spot anomalies visually - an indication of random error.

Shows that \(g\) is (more-or-less!) constant: the graph is a straight line.

Allows \(g\) to be determined from a gradient, an important skill.

Might lead on to a discussion about systematic errors (should the graph pass through the origin?).

Systematic errors can often be eliminated by plotting a graph. For example, if the height is measured 1 cm too short each time, the line on the graph will be shifted downwards. The gradient will be unchanged, and the systematic error should be easily detected.

Another approach, incidentally, would be to plot \(2s\) against \(t^2\), giving a simpler gradient of \(g\). This is a matter of personal preference.

Language:

Random error: a measurement error due to results varying in an unpredictable way.

Systematic error: A measurement error where results differ from the true value by a consistent amount each time.

Using light gates is a great way to get students familiar with data loggers. Watch out for the common misconception that using a computer will automatically give a better result! In this case, the timing typically does have a higher resolution, and it's possible to collect lots of data quickly - both good reasons for using the apparatus.

With two light gates, there are three possibilities:

Display values of \(u\) and \(v\), and calculate g using \(v^2 = u^2 + 2as\).

Display values of \(u\), \(v\) and \(t\), and calculate g using \(v = u - at\).

Position the top light gate just below where the ball is released so the initial velocity is close to zero, then proceed as above.

Note that the measured speeds are always average values, because the ball is accelerating during the time it takes to pass through the light gate.

Questions to ask your students:

Can we be sure that the data logger determines accurate times?

If we vary \(h\), what graph should we plot to determine \(g\)?

How can a graph help to reveal problems with the experimental technique?

Apparatus

If you don't have multiple sets of data loggers, you could have one set up and have students use it in turn. However, the experience of setting up the apparatus is itself valuable, as it prompts the student to think through the role of each piece of equipment rather than to approach the configured apparatus as a 'black box.'

The commercially available apparatus that Alom and Ronan discuss in the film is available from Philip Harris, for about £100+VAT. Instructions for its use are available from the Nuffield Foundation, which also includes circuit diagrams for a DIY version.

Ronan's version addresses several subtle issues, including that of releasing the ball cleanly, and using a plumb-line to confirm that \(h\) is being measured vertically. We'll update this article with more details of Ronan's apparatus when we have them.

Questions to ask your students

Between which two points should we measure the height of fall \(h\)?

Can we be sure that the timer starts and stops at the exact moments we want it to?

If we vary \(h\), what graph should we plot to determine \(g\)?

Common Practical Assessment Criteria

At the time of writing, the exam boards appear to agree that this practical might be used to address, in whole or in part:

CPAC 2: Applies investigate approaches and methods when using instruments and equipment.

CPAC 4: Makes and records observations.

Apparatus & Techniques

Each exam board has published a list of apparatus and techniques with which students much be familiar, along with suggestions as to which elements might be addressed by each practical. For example, Edexcel's guidance for this practical suggests:

1. Use appropriate analogue apparatus to record a range of measurements (to include length/distance, temperature, pressure, force, angles, volume) and to interpolate between scale markings

2. Use appropriate digital instruments, including electrical multimeters, to obtain a range of measurements (to include time, current, voltage, resistance, mass).

4. Use stopwatch or light gates for timing.

11. Use ICT such as computer modelling, or datalogger with a variety of sensors to collect data, or use of software to process data.

Check your exam board's resources: there should be a mapping document to help you decide which criteria to assess on each practical.

We've drafted a student worksheet for this practical, which you may find useful:

As ever, no single film can encompass everything one might wish to say about a practical. Please, leave comments with your thoughts about the approach we've taken, and your suggestions for alternatives or improvements.

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A-level specifications from all the exam boards include "measure the acceleration due to gravity of a freely falling body" as one of the practicals. Students might be a bit uninterested in measuring the value of a constant with which they are already familiar.

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Excellent website with loads of resources including exam questions on mandatory experiments but also a lovely document for marking students experiment copies.

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Preparation for the Leaving Cert Physics Exam on RTE

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PDST PowerPoint of all of the mandatory experiments. 

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PDST PowerPoint of all of the mandatory experiments. 

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Excellent for use in class or for flashcards for students for revision. Created by Jimmy Brophy.

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Investigate the variation of current with potential difference for (d) semiconductor diode

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Investigate the variation of current with potential difference for (d) semiconductor diode

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Investigate forward and reverse biased diodes.
Excellent simulation by Seán Foley (mathsphysics.com)

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When a voltage source is connected to a semiconductor diode (silicon) a current flows through the diode. In this experiment we investigate how the current flowing through the diode varies with different voltages applied across it when it is forward biased and when reverse biased.

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Procedure:

Note that the diode is forward biased and that current is 0 when voltage is 0. Record voltage and current values in a table.

Click on the slider to increase the voltage from the potentiometer.

Record the voltage and current readings from the voltmeter and ammeter.

Repeat steps 2 and 3 until you have exceeded the junction voltage and the current increases rapidly.

Set voltage to zero and click on "Reverse Biased". Note the changes that occur. Increase voltage and note current.

Analysis:
Draw a graph of current (y-axis) against voltage to determine the relationship between them. When the diode is forward biased the current is measured in milliamps, when reverse biased the current is measured in microamps. Make sure you understand the significance of the graph in terms of forward and reverse bias and junction voltage.

Precautions:

Use a microammeter when the diode is reverse biased as the current flowing is extremely small.

Change the positions of the microammeter and voltmeter when reverse biased so that the current flowing through the diode is the only one registered in the microammeter (not current through the voltmeter).

Electricity Experiments All Physics Experiments

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When a voltage source is connected to a semiconductor diode (silicon) a current flows through the diode. In this experiment we investigate how the current flowing through the diode varies with different voltages applied across it when it is forward biased and when reverse biased. Canvas not supported; please update your browser.

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Investigate the variation of current with potential difference for (c) copper sulphate solution with copper electrodes

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Investigate the variation of current with potential difference for (c) copper sulphate solution with copper electrodes

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Excellent simulation by Seán Foley (mathsphysics.com)

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When a voltage source is connected to a voltameter containing copper electrodes in a copper sulfate solution a current flows through the solution. In this experiment we investigate how the current flowing through the solution varies with different voltages applied across it.

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Procedure:

Note that current is 0 when voltage is 0. Record voltage and current values in a table.

Click on the slider to increase the voltage from the potentiometer.

Record the voltage and current readings from the voltmeter and ammeter.

Repeat steps 2 and 3 until you have at least six sets of readings.

Draw a graph of current (y-axis) against voltage to determine the relationship between them.
Note: Start both axes at zero. Draw a "best fit" straight line. Be sure you understand the significance of the graph.
Electricity Experiments All Physics Experiments

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When a voltage source is connected to a voltameter containing copper electrodes in a copper sulfate solution a current flows through the solution. In this experiment we investigate how the current flowing through the solution varies with different voltages applied across it. Canvas not supported; please update your browser.

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Investigate the variation of current with potential difference for (b) filament bulb

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Investigate the variation of current with potential difference for (b) filament bulb

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Excellent simulation by Seán Foley (mathsphysics.com)

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To investigate the variation of current ( I ) with pd ( V ) for a filament bulb When a voltage source is connected across a filament bulb a current flows through the filament causing it to get hot and emit light. In this experiment we investigate how the current flowing through the filament varies with different voltages applied to it.

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Procedure:

Note that current is 0 when voltage is 0. Record the voltage and current results in a table.

Click on the slider to increase the voltage from the potentiometer.

Record the voltage and current readings from the voltmeter and ammeter.

Repeat steps 2 and 3 until you have at least six sets of readings.

Analysis:
Draw a graph of current (y-axis) against voltage to find the relationship between them. Note: Start both axes at zero.
Be sure you understand and can explain why current does not continue to increase in a constant manner as voltage is increased.
Electricity Experiments All Physics Experiments

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To investigate the variation of current ( I ) with pd ( V ) for a filament bulb When a voltage source is connected across a filament bulb a current flows through the filament causing it to get hot and emit light.

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Investigate the variation of current with potential difference for (a) metallic wire

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Investigate the variation of current with potential difference for (a) metallic wire

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Excellent simulation by Seán Foley (mathsphysics.com)

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When a voltage source is connected to the ends of a metallic conductor (a piece of wire) a current flows through the conductor. In this experiment we investigate how the current flowing through the conductor varies with different voltages applied across the conductor.

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Procedure:

Note that current is 0 when voltage is 0. Record the voltage and current results in a table.

Click on the slider to increase the voltage from the potentiometer.

Record the voltage and current readings from the voltmeter and ammeter.

Repeat steps 2 and 3 until you have at least six sets of readings.

Analysis:
Draw a graph of current (y-axis) against voltage to find the relationship between them. Note: Start both axes at zero.
Draw a "best fit" straight line. A straight line through the origin shows that current is directly proportional to voltage.
The resistance of the wire can be calculated from the graph: R = V / I so resistance = slope. Precautions:

Use a low voltage so that the current flowing will be small enough that the temperature of the wire stays constant.

Use a sensitive milliameter and voltmeter to get accurate readings.

Electricity Experiments All Physics Experiments

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When a voltage source is connected to the ends of a metallic conductor (a piece of wire) a current flows through the conductor. In this experiment we investigate how the current flowing through the conductor varies with different voltages applied across the conductor. Canvas not supported; please update your browser.

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Excellent simulation by Seán Foley (mathsphysics.com)

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When a current flows through a heating element which is immersed in water in a calorimeter the temperature of the water rises. In this experiment we investigate how the temperature of the water and calorimeter change with the current flowing through the heating element. Note: In the lab. this is a very time consuming experiment as each different current must be allowed to flow for at least 5 minutes. In this simulation 90 seconds is sufficient for each current.

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Procedure:

Use the slider to set the current value to 0.5 A.

Note the starting temperature and current and record in a table.

Press "Close Circuit". Current begins to flow in the heating coil and the timer starts. Note: A very small rise in temperature occurs when the current is at 0.5 and 1A.

After 90s, press "Open Circuit". Record the rise in temperature.

Press "Reset" and again use the slider to set the current to 1 A. Record the starting temperature and current.

Repeat steps 3 to 5 until at least six readings have been taken.

Analysis:
Draw a graph, on graph paper, of Rise in Temperature versus Current squared. Start both axes at zero and draw a "best fit" line through the data points.

Ensure that the current remains constant at each value. Adjust the variable resistor if necessary.

Ensure that the heating coil is completely covered with water to avoid heat loss as measured by the thermometer.

Use a well insulated container.

Stir before taking temperature readings and take the highest value observed.

Electricity Experiments All Physics Experiments

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When a current flows through a heating element which is immersed in water in a calorimeter the temperature of the water rises. In this experiment we investigate how the temperature of the water and calorimeter change with the current flowing through the heating element. Note: In the lab.

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Measure the resistivity of the material of a wire

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Measure the resistivity of the material of a wire

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Excellent simulation by Seán Foley (mathsphysics.com)

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The resistivity (ρ) of a material is one of the factors that determines the resistance of that material to the flow of electric current through it. In this experiment you measure the resistance (R) of a length of nichrome wire (length l) using an ohmmeter. You then measure the diameter (d ) of the wire using a micrometer screw guage. The resistance is given by the formula: R = ρ.l / A, where A is the cross-sectional area of the wire (A = πr²). The resistivity can be calculated from the formula: ρ = R.A / l.

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Procedure:

Drag the slider to move the contact along the wire. At some point, record the resistance and the length of the wire.

Press "Get Micrometer". In this simulation a full turn of the circular scale reads from 0 to 50 and represents 0.5 mm. Note: initial reading = 3.72 mm, distance scaled up a little to make it more readable.

Press "Check Zero Error". A reading between 0.00 and 0.03 will show and therefore will have to be subtracted from later readings.

Press "Measure Diameter". Record the value and repeat until you have at least six readings. Calculate the average diameter.

Calculate the resistivity of the material of the wire.

Move the slider and therefore the sliding contact to a new position on the wire and again record length and resistance and again calculate resistivity.

Ensure that the wire is straight when measuring its length. Measure only between the ohmmeter contacts.

Take great care with the micrometer screw guage and the zero error, if present. Take the average of at least six readings as a very small error in the diameter of the wire causes a large error in the resistivity calculated.

To avoid errors in the resistance readings press the ohmmeter contacts together and zero the ohmmeter, or else subtract the resistance of contacts and connections from later readings.

Electricity Experiments All Physics Experiments

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The resistivity (ρ) of a material is one of the factors that determines the resistance of that material to the flow of electric current through it. In this experiment you measure the resistance (R) of a length of nichrome wire (length l) using an ohmmeter.

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Investigate the variation of resistance of a thermistor with temperature

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Investigate the variation of resistance of a thermistor with temperature

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Excellent simulation by Seán Foley (mathsphysics.com)

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The electrical resistance of a thermistor depends on its temperature. In this experiment a thermistor is connected to an ohmmeter to measure its resistance. The temperature of the thermistor is then slowly incresed by placing it in a test tube of glycerol which is, in turn, placed in a beaker of water which is heated. The water is heated slowly and resistance readings are taken at a number of different steady temperatures. The resistance of the thermistor drops very quickly with increasing temperature so take resistance readings after small temperature increases at the start of the experiment.

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Procedure:

Record the starting temperature and the resistance reading in a table.

Press "Heater On".

After a rise of 3 or 4 degrees press "Heater Off". Wait until the temperature stops rising as in the real world. Record the temperature and resistance values.

Repeat steps 2 and 3 until you have recorded at least six sets of readings. Larger temperature increases (8 deg.) or more can be used as the experiment proceeds.

To repeat the experiment press "Reset" and repeat the experiment procedure.

Heat very slowly to try to maintain thermal equilibrium between the water and glycerol and coil. When the heater is switched off wait until the temperature is steady before taking the resistance readings.

Use glycerol in the test tube as it is a better heat conductor than water.

Electricity Experiments All Physics Experiments

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The electrical resistance of a thermistor depends on its temperature. In this experiment a thermistor is connected to an ohmmeter to measure its resistance. The temperature of the thermistor is then slowly incresed by placing it in a test tube of glycerol which is, in turn, placed in a beaker of water which is heated.

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Investigate the variation of resistance of a metallic conductor with temperature

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Investigate the variation of resistance of a metallic conductor with temperature

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Excellent simulation by Seán Foley (mathsphysics.com)

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One of the factors that affects the electrical resistance of a metal is the temperature of the metal. In this experiment a length of wire, wound on a solid former, is connected to an ohmmeter to measure its resistance. The temperature of the wire is then slowly incresed by placing it in a test tube of glycerol which is, in turn, placed in a beaker of water which is heated with a laboratory heater. The water is heated slowly and resistance readings are taken at a number of different steady temperatures.

Canvas not supported; please update your browser.

Procedure:

Record the starting temperature and the resistance reading in a table.

Press "Heater On".

After a rise of approx. 8 degrees press "Heater Off". Wait until the temperature stops rising. Record the temperature and resistance values.

Repeat steps 2 and 3 until you have recorded at least six sets of readings..

To repeat the experiment press "Reset" and repeat the steps described above.

Check for the resistance of the connecting leads and contacts on the ohmmeter. Subtract from later readings.

Heat very slowly to try to maintain thermal equilibrium between the water and glycerol and coil. When the heater is switched off wait until the temperature is steady before taking the resistance readings.

Use glycerol in the test tube as it is a better heat conductor than water.

Electricity Experiments All Physics Experiments

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One of the factors that affects the electrical resistance of a metal is the temperature of the metal. In this experiment a length of wire, wound on a solid former, is connected to an ohmmeter to measure its resistance.

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Lovely interactive virtual lab as students can change diameter and also the surrounding temperature when measuring the speed of sound. Two factors that are not really possible in the lab.

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Resonance Column (Simulator) : Class 11 : Physics : Amrita Online Lab

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To find the speed of sound in air at room temperature using a resonance tube by two resonance positions.

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Investigate the variation of the fundamental frequency of a stretched string with tension

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Investigate the variation of the fundamental frequency of a stretched string with tension

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Signal generator and magnet version.
Excellent simulation by Seán Foley (mathsphysics.com)

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Every object has a natural frequency of vibration. If kinetic energy is applied to an object at a rate that matches its natural frequency, resonance occurs and the object vibrates. In this experiment a small current, produced by a signal generator, causes the sonometer wire to move up and down due to interaction with the magnetic field of a U-shaped magnet. When the rate of movement due to the current matches the fundamental frequency of the wire, resonance occurs causing noticeable vibration. If the tension on the wire is increased (length kept constant), the resonant frequency of the wire also increases.

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Procedure:

Press the "Signal ON" button.

Adjust the frequency of the signal current using the right hand slider at the bottom.

When maximum vibration occurs, press the "Signal OFF" button.

Record the frequency of vibration of the wire (Hz) and the tension (N) in the Newton meter.

Using the left hand slider change the tension in the wire.

Repeat steps 1 to 6 until you have at least six sets of tension and frequency readings.

Graph:
On graph paper, draw a graph of frequency against the square root of the tension(x-axis). Start both axes at zero.
A straight line graph through the origin shows that frequency is proportional to square root of tension.

Precautions:

Ensure that the length is kept constant (the bridges do not move) as the tension is changed.

If a paper rider is used to locate resonance, place it mid-way between the bridges.

Sound Experiments All Physics Experiments

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Every object has a natural frequency of vibration. If kinetic energy is applied to an object at a rate that matches its natural frequency, resonance occurs and the object vibrates. In this experiment a small current, produced by a signal generator, causes the sonometer wire to move up and down due to interaction with the magnetic field of a U-shaped magnet.

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Investigate the variation of the fundamental frequency of a stretched string with length

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Investigate the variation of the fundamental frequency of a stretched string with length

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Signal generator and magnet version.
Excellent simulation by Seán Foley (mathsphysics.com)

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Every object has a natural frequency of vibration. If kinetic energy is applied to an object at a rate that matches its natural frequency, resonance occurs and the object vibrates. In this experiment a small current, produced by a signal generator, causes the sonometer wire (must be a conductor) to move up and down due to interaction with the magnetic field of a U-shaped magnet. When the frequency of the a.c. current matches the fundamental frequency of the wire, resonance occurs causing noticeable vibration of the wire. In this simulation only the fundamental frequency is found, no harmonics.

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Procedure:

Press the "Signal ON" button.

Adjust the frequency of the signal current using the right hand slider at the bottom.

When maximum vibration occurs, press the "Signal OFF" button.

Press "Get ruler" to measure the length of the wire.

Record the length of the wire (m) and the frequency.

Using the left hand slider move the bridge a little to the right. The magnet stays midway between the bridges.

Repeat steps 1 to 6 until you have at least six sets of length and frequency readings.

Graph: On graph paper, draw a graph of frequency against 1 / length (x-axis). Start both axes at zero.
A straight line graph through the origin shows that frequency is proportional to 1 / length (i.e. frequency is inversely proportional to length).

Precautions:

To avoid parallax errors, ensure that your eye is directly above the ruler when measuring the length of the wire.

Ensure that the tension remains constant throughout as the bridges are moved.

Sound Experiments All Physics Experiments

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Every object has a natural frequency of vibration. If kinetic energy is applied to an object at a rate that matches its natural frequency, resonance occurs and the object vibrates. In this experiment a small current, produced by a signal generator, causes the sonometer wire (must be a conductor) to move up and down due to interaction with the magnetic field of a U-shaped magnet.

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Measure the specific heat capacity of vaporisation of water

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Measure the specific heat capacity of vaporisation of water

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Excellent simulation by Seán Foley (mathsphysics.com)

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When steam, at 100 degrees celsius, is bubbled into water, it first condenses to water and then its temperature decreases as it loses heat to the surrounding water. If this occurs in an insulated container then the heat lost by the steam is equal to the heat gained by the water and the container. The specific latent heat of vaporisation of water (l) can then be calculated using the formula: m s l + m s c w(fall in temp of condensed steam) = m c c c (rise in temp of calorimeter) + m w c w (rise in temp of water) where m s, m c and m w are the masses of steam, calorimeter and water respectively and c w and c c are the specific heat capacities of water and of the material of the calorimeter. Note: c copper = 390 J / kg / K, c aluminium = 910 J / kg / K, c polystyrene = 0.

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Procedure:

To select different calorimeters click on the word "Copper" for other options. Mass is shown in the top pan balance.

Click in the Mass box and select the mass of water in the calorimeter. (min.50g, max. 90g). Press Submit.

Click on "Place Calorimeter" to put the calorimeter in the insulated container.

Record the starting temperature, mass of water, mass of calorimeter, and the material of the calorimeter.

Press "Add Steam" to allow steam from the steam generator to pass to the water in the calorimeter.

After a temperature rise of 10 to 15 degrees, the steam pipe is removed (happens automatically here) so heating is stopped. Record temperature.

Press "Get Total Mass" to find the mass of calorimeter + water + steam. Record.

Press "Reset".

Repeat the experiment using a variety of calorimeters and masses of water.

Ensure that only steam (not water) enters the water in the calorimeter. Use a "steam trap" (it actually traps water) if available.

Ensure that the calorimeter is well insulated to avoid loss or gain of heat energy.

Stir the water throughout the experiment to ensure that the thermometer reading reflects the heat supplied.

Use a sensitive thermometer graduated to 0.1 or 0.2 degrees. An error of 1 deg. in 10 is a large relative error.

Use cooled water (about 5 deg. below room temp.) at the start of the experiment so that, overall, heat is neither lost nor gained from the surroundings.

Heat Experiments All Physics Experiments

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When steam, at 100 degrees celsius, is bubbled into water, it first condenses to water and then its temperature decreases as it loses heat to the surrounding water. If this occurs in an insulated container then the heat lost by the steam is equal to the heat gained by the water and the container.

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Measure the specific heat capacity of fusion of ice

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Measure the specific heat capacity of fusion of ice

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Excellent simulation by Seán Foley (mathsphysics.com)

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When ice, at zero degrees celsius, is added to warm water, it first melts and then its temperature increases as it takes heat from the water. If this occurs in an insulated container then the heat gained by the ice is equal to the heat lost by the container and the water. The specific latent heat of fusion of ice (l) can then be calculated using the formula:

m i l + m i c w (rise in temp of melted ice) = m c c c (fall in temp of calorimeter) + m w c w (fall in temp of water)

where m i, m c and m w are the masses of ice, calorimeter and water respectively and c w and c c are the specific heat capacities of water and of the material of the calorimeter.

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Procedure:

To select a calorimeter click on the word "Copper" for other options. Mass is shown in the top pan balance.

Click in the Mass box and select the mass of water in the calorimeter. (min.50g, max. 90g). Press Submit.

Click on "Place Calorimeter" to put the calorimeter in the insulated container.

Record the starting temperature, mass of water, mass of calorimeter, and the material of the calorimeter.

Press "Add Ice" to add dry crushed ice to the water in the calorimeter.

After a temperature fall of 10 to 15 degrees, the temperature stops falling.

Press "Get Total Mass" to find the mass of calorimeter + water +ice. Record.

Press "Reset".

Repeat the experiment using a variety of calorimeters and masses of water.

Ensure that only ice (not water) enters the water in the calorimeter. The melting ice should be dabbed with abosrbent paper.

Ensure that the calorimeter is well insulated to avoid loss or gain of heat energy.

Stir the water throughout the experiment to ensure that the thermometer reading reflects the actual temperature.

Use a sensitive thermometer graduated to 0.1 or 0.2 degrees. An error of 1 deg. in 10 is a large relative error.

Use warmed water (about 5 deg. above room temp.) at the start of the experiment so that, overall, heat is neither lost nor gained from the surroundings.

Heat Experiments All Physics Experiments

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When ice, at zero degrees celsius, is added to warm water, it first melts and then its temperature increases as it takes heat from the water. If this occurs in an insulated container then the heat gained by the ice is equal to the heat lost by the container and the water.

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Measure the specific heat capacity of water 

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Measure the specific heat capacity of water 

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Excellent virtual lab.

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Plot the calibration curve of a thermometer

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Plot the calibration curve of a thermometer

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Uncalibrated alcohol thermometer against standard lab mercury thermometer.
Excellent simulation by Seán Foley (mathsphysics.com)

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An unmarked thermometer (alcohol in this expt.) can be calibrated using a mercury thermometer as a standard. Both thermometers are placed in melting ice (0 degrees C). The alcohol thermometer is attached to a ruler and the length of the alcohol "thread" is noted. A heater is switched on causing the water temperature to gradually increase. For at least six temperature values, read from the mercury thermometer, the corresponding length of the alcohol thread is noted. A graph of length of alcohol thread against temperature is the required calibration curve.

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Procedure:

Familiarise yourself with the scale on the thermometer and on the ruler. Note the starting temperature and the length of the alcohol thread.

Press " Heater On".

As the temperature increases note the temperature and the corresponding length of the alcohol in the unmarked thermometer at least six times.

The hotplate stops automatically when the temp. reaches 100 degrees Celsius. If you want to repeat the experiment press "Reset" and repeat steps 2 and 3.

Analysis:
Plot a graph, on graph paper, of length of alcohol thread (y-axis) against temperature. In the lab. any temperature between 0 and 100 degrees can now be measured using the unmarked thermometer. Place it in a beaker of moderately hot water, measure the length of the alcohol thread and, from the calibration curve, read the corresponding temperature.

Precautions:

Place both thermometers in melting ice (0 deg. C) for a few minutes at the start of the experiment to allow readings to stabilise.

Heat the water very slowly so that it is easy to take temperature and length readings simultaneously.

Have your eye level with the liquid columns when taking temperature and length readings to avoid parallax errors

Heat Experiments All Physics Experiments

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An unmarked thermometer (alcohol in this expt.) can be calibrated using a mercury thermometer as a standard. Both thermometers are placed in melting ice (0 degrees C). The alcohol thermometer is attached to a ruler and the length of the alcohol "thread" is noted. A heater is switched on causing the water temperature to gradually increase.

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Measure the wavelength of monochromatic light

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Measure the wavelength of monochromatic light

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Lovely simulation to find the wavelength of monochromatic light using a laser. You can vary the wavelength, vary the grating constant and also distance to screen.

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Description
This is a simulation of a typical laser diffraction lab set up. Examine the set up in the 3D window, it shows a laser, a diffraction grating, and a screen. Use the checkbox to place the grating in front of the laser, and look at the pattern of dots that appear on the screen. Use the sliders to change the distance from the grating to the screen, the number of lines per millimeter in the diffraction grating, and the wavelength of the laser. Use the diagram of the screen in the top window to analyze the numerical positions of the dots on the screen using diffraction equations.

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Description This is a simulation of a typical laser diffraction lab set up. Examine the set up in the 3D window, it shows a laser, a diffraction grating, and a screen. Use the checkbox to place the grating in front of the laser, and look at the pattern of dots that appear on the screen.

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Measure the focal length of a convex lens

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Measure the focal length of a convex lens

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The first part of this simulation can be used to find the focal length of the convex lens. Students do not need to do the second half of the experiment as they do not need to know how to find the focal length of a convex mirror.

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Convex Mirror - Focal Length (Simulator) : Class 12 : Physics : Amrita Online Lab

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Find the focal length of a convex mirror using a convex lens

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Measure the refractive index of a liquid/solid

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Measure the refractive index of a liquid/solid

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Excellent simulation of finding the refractive index of water.

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An object pin, placed at the bottom of a container of water, when viewed from above, appears to be less deep than it actually is. This apparent depth can be measured by finding the position of no parallax between the image of the object pin and the image of a search pin, placed above the container and viewed in a plane mirror which is resting on top of the container. When there is no parallax between the images it means that both images are equidistant from the eye of the observer.
The refractive index (n) of the water is calculated using the formula: n = Real depth / Apparent depth.

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Procedure:

Using the slider, drag the search pin to rougly the correct height above the container.

Press the "Move Eye" button.

The image which is farther away appears to move relative to the other (parallax). Raise or lower the search pin and again press "Move Eye". Repeat until you find the position of no parallax (no movement).

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Press the "Get Ruler" button.

Measure and record the real depth and the apparent depth and divide to find n.

Press the "Container 2" button and repeat steps 1 to 5.

Press the "Container 3" button and repeat steps 1 to 5.

Press "Reset" to start over.

Precautions:

Ensure that the water is touching the back of the mirror.

Avoid parallax errors when reading the real and apparent depths. Have your eye directly in line with the ruler and object.

Light Experiments All Physics Experiments

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An object pin, placed at the bottom of a container of water, when viewed from above, appears to be less deep than it actually is. This apparent depth can be measured by finding the position of no parallax between the image of the object pin and the image of a search pin, placed above the container and viewed in a plane mirror which is resting on top of the container.

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Excellent simulation by Seán Foley (mathsphysics.com). Students can investigate the refractive index of both glass and perspex.

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When light rays pass from one medium to another (different density), they change direction (are refracted). When they enter a more dense medium they bend towards a normal line drawn at the point of incidence. In this experiment we investigate the relationship between the angles of incidence and of refraction for light rays travelling into perspex and into glass. Using these angles, or a suitable graph, we can then find the refractive index of perspex and of glass.

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Procedure:

Click on the radio button for Glass or Perspex to select the material of the block (the default material is glass).

Using the slider, move the ray box a little to the right.

Press "Measure i" and record its value.

Press "Measure r" and record its value.

Use the formula: n = sin i / sin r to calculate n.

Repeat steps 1 to 5 until you have at least six sets of readings. Find the average value of the refractive index of the material of the block.

Repeat the procedure for the other medium to find the value of the refractive index for that medium.

Perspex

Graph: Draw a graph of Sin i (y-axis) against Sin r (start both axes at zero). A straight line graph (best fit) through the origin shows that Sin i is proportional to Sin r. Select two suitable points on the graph (far apart) to find the slope of the graph. This is an average value for the refractive index of the medium.
Precautions:

Avoid using small angles of incidence as errors in reading the angles would then be relatively large.

When doing this experiment in the lab. place two dots far apart on the incident and refracted light beams to accurately locate the beams.

Light Experiments All Physics Experiments

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When light rays pass from one medium to another (different density), they change direction (are refracted). When they enter a more dense medium they bend towards a normal line drawn at the point of incidence. In this experiment we investigate the relationship between the angles of incidence and of refraction for light rays travelling into perspex and into glass.

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Measure the focal length of a concave mirror

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Measure the focal length of a concave mirror

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Lovely virtual lab which allows you to enter data into your results table and zooms in on ruler making it easier to read.

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The Concave mirror - u-v method (Simulator) : Class 12 : Physics : Amrita Online Lab

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To determine the focal length of athe given concave mirror by u-v method.

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Measure acceleration due to gravity (simple pendulum)

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Measure acceleration due to gravity (simple pendulum)

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PhET simulation. Excellent way of taking this experiment one step further by looking at gravity and friction. Students can also see that by changing the mass the period remains the same.

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Investigate the laws of equilibrium for a set of coplanar forces

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Investigate the laws of equilibrium for a set of coplanar forces

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Excellent simulation by Seán Foley (mathsphysics.com)

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In this experiment a metre stick is suspended from two newton balances and four masses are hung from the stick. The masses are changed or moved around until the stick is level. The two conditions for equilibrium should then hold:
(i) the total force up = total force down
(ii) for any point on (or off) the metre stick the sum of the clockwise moments = the sum of the anticlockwise moments.
Note: Masses can be changed using the M+ and M- buttons and can be moved with the sliders. The weight of the metre stick, at the 50 cm mark, is 1 N and each hanging mass is 20 g. A small spirit level (assumed weightless) sitting on the stick indicates when it is level (remember the bubble always goes to the high side).

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Procedure:

The sliders allow you to move the masses. The M+ and M- buttons allow you to change the masses.

Change and move the masses until you get the system in equilibrium (the bubble in the middle)

Into your copy draw the forces acting on the stick (don't forget the weight of the stick) and the position of each of the forces.

Pick any point on the stick and calculate the sum of the clockwise moments and the sum of the anticlockwise moments about that point.

Analysis:
It is easiest to calculate moments about the zero mark of the metre stick. Convert the masses to weights and don't forget the weight of the stick.

Precautions:

Check that the centre of gravity is at the 50 cm mark on the metre stick

Ensure that the Newton balances are vertical and the metre stick is horizontal when readings are taken.

Mechanics Experiments All Physics Experiments

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In this experiment a metre stick is suspended from two newton balances and four masses are hung from the stick. The masses are changed or moved around until the stick is level.

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PhET simulation which gives a lovely visual of the fixed mass of gas in Boyle's Law.

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Verify the principle of conservation of momentum

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Verify the principle of conservation of momentum

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Excellent simulation from Seán Foley (mathsphysics.com)

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In this experiment a trolley is pushed down a runway which is tilted at an angle so that the speed of the trolley remains constant. It then collides with and sticks to a second trolley and they travel together to the end of the runway. The velocity of the trolley is measured just before and after the collision. If the masses of both trolleys are known the momentum before and after the collision can be calculated. Momentum = (mass)(velocity) Note: In this simulation the mass of each trolley is 1 kg and the moveable masses are each 0.2 kg.

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Procedure:

Note the mass on each trolley

Press "Push Trolley".

Press "Get Tape and Ruler".

Measure and record a five-space distance (5/50 s) just before collision.

Calculate "u" = distance/0.1. Calculate "v" in a similar way after collision.

Press "Reset".

Press "Move Mass" and repeat steps 1 to 6 until the three masses have been transferred to trolley 2

Analysis:
For each collision calculate the momentum before the collision and the momentum after. The results, subject to small experimental error, should be equal thus verifying the principle of conservation of momentum.
Precautions:

Ensure that the runway is tilted just enough for the trolleys to roll at constant speed when given a gentle push.

Ignore a few dots on either side of the collision. These may be unreliable.

Place a ruler right on top of the tape with eye directly above when measuring distances to avoid parallax errors

Mechanics Experiments All Physics Experiments

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In this experiment a trolley is pushed down a runway which is tilted at an angle so that the speed of the trolley remains constant. It then collides with and sticks to a second trolley and they travel together to the end of the runway.

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Show acceleration of a body is directly proportional to the force acting on it

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Show acceleration of a body is directly proportional to the force acting on it

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Excellent simulation from Seán Foley (mathsphysics.com)

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When a free running trolley accelerates as a result of a force applied to it the acceleration is proportional to the applied force. In this experiment the overall mass of the system is kept constant but masses are moved from the trolley to the end of a string which is hanging over a free moving pulley. As the number of "weights" attached to the end of the string increases (the accelerating force), the acceleration increases. We will investigate the relationship between acceleration and accelerating force. A ticker timer is used to measure the acceleration.
Note: In this simulation the trolley is running on a level track. In the lab a level air track can be used or a simple runway which is tilted sufficiently to overcome friction in the wheels of the trolley and in the pulley. The mass of the trolley is 1.2 kg and the masses are 200 g each.

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Procedure:

Press "Release Trolley".

Press "Get Tape and Ruler".

Measure a 5 dot interval near the start of the tape. This distance was travelled in 5/50 of a second. Calculate u, the initial velocity. u = distance / 0.1 m/s

Measure and record a 5 dot interval near the end of the tape and calculate v.

Count the number of dots from the start of the first interval to the start of the second. Time is given by: t = no. of dots / 50

Calculate the acceleration using the formula a = (v - u) / t

Press "Reset" and "Move Mass" to transfer a mass from the trolley to the string and repeat steps 1 to 6.

To completely restart the experiment press "Full Reset".

Ensure that the runway in smooth, free of dust, and does not sag in the middle

Ignore the first few dots on the tape. These are unreliable and too close together for accurate measurement.

Place a ruler right on top of the tape with eye directly above when measuring distances to avoid parallax errors

Mechanics Experiments All Physics Experiments

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To show that acceleration is proportional to force

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When a free running trolley accelerates as a result of a force applied to it the acceleration is proportional to the applied force. In this experiment the overall mass of the system is kept constant but masses are moved from the trolley to the end of a string which is hanging over a free moving pulley.

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Measure acceleration due to gravity (freefall)

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Measure acceleration due to gravity (freefall)

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Excellent simulation from Seán Foley (mathsphysics.com)

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In this experiment a ball is dropped from an electromagnet or other mechanism onto a trapdoor. When the ball is released a timer is started. When the ball hits the trapdoor the timer is stopped. If the distance from the ball to the trapdoor is measured the acceleration due to gravity (g) can be calculated. Use the formula; s = ut + ½at² and note that u = 0 and a = g.

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Procedure:

Click "Get Ruler". Measure and record the distance from the trapdoor to the bottom of the ball (s)

Click "Drop Ball" to release the ball and start the timer. Record the time (t) for the ball to fall the measured distance. In the physics lab. the ball should be allowed to fall at least three times and the shortest time recorded. Not necessary here.

Click "Reset".

Click "Lower Ball". The release mechanism falls by a random amount thus changing the distance through which the ball will fall the next time

Repeat steps 1 to 4 until at least six sets of results are collected

Calculate g for each s value and its corresponding t value using the formula given above.

Plot a graph of s (y-axis) against t². Draw a "best fit" straight line and measure its slope. Since s = ½gt², the value of g is calculated by g = 2 × slope.

Precautions:

Record the shortest time of fall for each height

Place a piece of paper between the ball and the electromagnet to ensure that the ball falls immediately when the switch is flicked

Use large distances as much as possible so that measurement errors (distance and time) are relatively small.

Mechanics Experiments All Physics Experiments

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In this experiment a ball is dropped from an electromagnet or other mechanism onto a trapdoor. When the ball is released a timer is started. When the ball hits the trapdoor the timer is stopped. If the distance from the ball to the trapdoor is measured the acceleration due to gravity (g) can be calculated.

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Measure constant velocity and constant acceleration

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Measure constant velocity and constant acceleration

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Excellent simulation from Seán Foley (mathsphysics.com).

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In this experiment a trolley is allowed to roll down a runway which is tilted at an angle. The runway must first be tilted to overcome the friction in the wheels of the trolley. A ticker tape timer is used to measure the velocity near the start of its journey (u) and near the end(v). The acceleration can then be calculated. Note: In this simulation the angle of the runway can be changed by dragging the slider right or left.

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Procedure:

Using the slider below the simulation, raise the runway a few degrees.

Press "Release Trolley". If the trolley does not move raise the runway a little more and try "Release Trolley" again. When friction is overcome the trolley accelerates very slowly. In the lab, at a slightly lower angle, a little push would make it move with constant velocity.

Press "Get Tape and Ruler".

Measure and record a five-space distance (5/50 s) near the start

Calculate "u" = distance/0.1. Calculate "v" in a similar way near the end of the tape

Calculate the acceleration using the formula a = (v - u) / t where t is the number of dots from start of u interval to start of v interval / 50.

Press reset and try different angles

Note:Because of the small space available the accelerations calculated in this simulation are much too large.
Precautions:

Ensure that the runway in smooth, free of dust, and does not sag in the middle

At constant velocity the dots must be equally spaced all along the tape (same distance for each 1/50th. sec.). Not possible with this simulation.

Ignore the first few dots on the tape. These are unreliable and too close together for accurate measurement.

Place a ruler right on top of the tape with eye directly above when measuring distances to avoid parallax errors

Mechanics Experiments All Physics Experiments

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In this experiment a trolley is allowed to roll down a runway which is tilted at an angle. The runway must first be tilted to overcome the friction in the wheels of the trolley. A ticker tape timer is used to measure the velocity near the start of its journey (u) and near the end(v).

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Flash cards to aid key tips for each mandatory experiment created by Máire Duffy.