P2 Revision Part III - Electricity - Tasks 1-12 by Mr V

Task 1 - Static electricity

MrVieito — 2015-03-01 15:36:54 UTC

Use the diagram to explain what happens to create a static charge, what does the moving, why it moves and why it stays on the object.

If an object gains electrons does it become negatively or positively charged?

Task 2 - Draw three circuits symbols one where you use all the components listed below.

MrVieito — 2015-03-01 15:41:11 UTC

Take care with how you place the ammeter and voltmeter in the circuit.

Task 3 - Which circuits will work?

MrVieito — 2015-03-01 15:43:40 UTC

Task 4 - Electrical current is the flow of charge. You know?

MrVieito — 2015-03-01 15:44:44 UTC

Electrical current is the flow of charge. Electrical current is the flow of charge. Electrical current is the flow of charge. Electrical current is the flow of charge.

And charge is measured in (C) Coulombs.

Calculate: A cell transfers 75 C of charge to a filament lamp over a period of 60 seconds at a constant current. What is the size of the current?

Higher: A battery charger passes a current of 2.5 A through a cell over a period of 4 hours. How much charge does the charger transfer to the cell altogether?

Task 5 - Potential difference is the work done per unit of charge.

MrVieito — 2015-03-01 15:48:21 UTC

Measured in volts, it's basically a measure of energy per coulomb.

Calculate: It takes 720 kJ of energy to move a charge of 50 000 C through an electric motor. Calculate the potential difference across the motor.

Higher: The potential difference across a lamp in a circuit is 2.3 V. The current in the circuit is 0.5 A. How much energy is transferred by the lamp if it is lit for 2 minutes?

Task 6 - Resistance reduces the flow of electrical current. The equation is often referred to as Ohm's Law.

MrVieito — 2015-03-01 15:52:23 UTC

Calculate: The ammeter in the circuit shown reads 3.4 A and the resistance of the resistor is 5.6 Ω. What is the p.d. across the resistor?

Voltmeter V reads 6 V and resistor R is 4 Ω. What is the current through ammeter A?

Task 7 - Calculating the resistance of a component.

MrVieito — 2015-03-01 15:56:41 UTC

You need to know how to set up the circuit for this experiment. Memorise it then try and redraw it from memory.

Task 8a - Non-Ohmic resistors

MrVieito — 2015-03-01 16:01:01 UTC

A filament bulb does not obey Ohm's Law. You need to be able to explain why.

When an electrical charge flows through a component with resistance, some of the electrical energy is transferred to heat energy and the component gets hot.

This heat energy causes the ions in the conductor to vibrate more. With the ions jiggling around it’s more difficult for the charge-carrying electrons to get through the component — the current can’t flow as easily and the resistance increases.

increases.

Task 8 - Ohmic resistors

MrVieito — 2015-03-01 16:01:31 UTC

Will have a directly proportional relationship between current and potential difference

Task 9 - Is a diode an Ohmic resistor?

MrVieito — 2015-03-01 16:10:01 UTC

Can you explain why?

Task 10 - LED's

MrVieito — 2015-03-01 16:10:40 UTC

There are often questions that ask you to compare LED's to filament bulbs.

Task 11 - LDR's

MrVieito — 2015-03-01 16:16:17 UTC

Explain how the resistance of Light Dependent Resistor changes with light

Task 12 - Thermistors

MrVieito — 2015-03-01 16:16:21 UTC

Explain how the resistance of a thermistor changes with temperature

P2 revision

MrVieito — 2016-03-13 07:57:37 UTC