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Hi Teacher Josh

I think I might be mixing up the x axis but, how do I find the half life in this graph. I thought it would be 7 days but the answer says otherwise. (It does not give a worked solution =0 )

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This question links work with power. I am unsure how to approach this question and what im trying to find. I have a feeling it is something to do with Power = the rate of change of work done. I also know that we have to use the EMF formula to find the emf. But im unsure how to approach this question.

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Electromotive force: Electromotive force is the energy provided by a source per unit charge to move electric charges around a complete circuit.

Ohms law: current through a conductor is directly proportional to the voltage across it and emf is equal to IR.

When solving for r, since this is a series circuit we just add the resistance to get the total resistance in the circuit. the total resistance will be the resistor + the internal resistor meaning R + r and know we reaggange to find r. With this we get 0.56 ohms

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Complete this ASAP (then ask for the worked solution)

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Complete this ASAP (then ask for the worked solution)

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A4 Rigid Body Motion Paper 2 Exam Question

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Why are some isotopes more stable than others

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Why are some isotopes more stable than others

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Some isotopes could be more stable than others because of the balance between the number of protons and neutrons. There is a trend as the mass increases, the number of neutrons increase and protons decrease. This is because when there is more mass the size of the nucleus becomes bigger hence more neutrons are needed to maintain the binding energy. If there are too many protons then the nucleus could collapse.

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Induced fission is a nuclear reaction in which a heavy atomic nucleus, such as uranium-235, splits into two smaller nuclei after absorbing a neutron. This process releases a large amount of energy, along with more neutrons, which can then trigger further fission reactions

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Spontaneous fission is a type of nuclear reaction where a heavy atomic nucleus splits on its own. It occurs naturally in some unstable isotopes -uranium-238, and releases energy, smaller nuclei, and neutrons. However, it is less common than induced fission.

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Follows the formula ( deltaM = Mnuc - (Z(Mp)+(Z-A)(Mn)). Mass defect is the difference between the total mass of the individual protons and neutrons in an atomic nucleus and the actual mass of the nucleus itself. This left over mass has been converted into binding energy that holds the nucleus together

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Calculate using the N.B.E because it is more accurate and represents the amount of energy required to break each individual bond instead of an average for the whole nucleus.

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Nuclear binding energy

--> Find the total nuclear binding energy and divide by (A) total neutrons + protons. Represents the binding energy between each proton and neutron.

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Mev --> eV

=1 x 10⁶

eV --> J

= 1 x ( 1.6 x 10-19 )

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Nuclear fusion is a reaction where two light atomic nuclei combine to form a heavier nucleus, releasing a huge amount of energy in the process.

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Nuclear fission is a reaction in which a heavy atomic nucleus splits into two smaller nuclei, along with the release of energy, neutrons, and radiation.

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Radioactive waste decays in the order of alpha or beta minus / plus decay, then gamma decay. All types of radiation are dangerous, but gamma radiation are the most dangerous to living organisms as they have the greatest penetrative ability of the different types of radiation, while alpha and beta radiation aren't able to penetrate human skin and tissue as easily. While gamma radiation's ionizing power is not as strong as the other types of radiation, the energy it releases is immense and will still be very harmful to living organisms when exposed, damaging the DNA structure and causing cancer cells to form and develop into tumors.

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Slides about the electron model in everyday technology 

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Slides about the electron model in everyday technology 

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https://docs.google.com/presentation/d/1DLaZ6iTWHnF5uvRPocJj7Qb8YM04k_1QTpbGILn6hvk/edit?usp=sharing

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The minimum frequency of electromagnetic radiation needed to eject electrons from a metal surface in the photoelectric effect

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Intensity of light ∝ ejection rate

Higher wavelength 1/∝ ejection rate

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It is the wavelength associated with a moving particle, inversely proportional to its momentum.

The formula for calculating the de Broglie wavelength (λ) is λ = h/p, where h is Planck's constant and p is the particle's momentum.

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Mass defect is used when calculating the energy released or absorbed in nuclear reactions or when comparing the mass of a nucleus to the sum of its constituent nucleons.

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2 protons and 2 neutrons are released

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Proton --> neutron

and this emits a positron and neutrino

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Emites an Electron and an antineutrino

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R = RoA1/3

so density (p)

p ∝ 1/R³ ∝1/A

M∝A

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My thoughts:

When electricity flows through the coils, it goes in loops creating a magnetic field. When a magnetic field is created and is in an A.C circuit, the direction changes creating an electric field. This electric field will charge the induction coil in the phone, converting the energy into electricity.

What chatGPT said:

An induction coil in a wireless phone charger is a coil of wire that generates a changing magnetic field when alternating current (AC) flows through it. This alternating magnetic field induces an electric current in the receiving coil inside the phone, wirelessly transferring energy and converting it into electricity to charge the battery.

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Ek translational = 1/2 MV²

Ek rotational = 1/2 IW²

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W is the rate of change of the angle.

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PD has its units calculated in VOLTS. TO better understand volts it is the amount of energy needed to move 1kg or 1C from infinity to a point in tje field. So delta v = JC⁻¹

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Faradays law is the rate of change of magnetic flux and how it relates to E.M.F. The (-) shows the direction of motion.

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S - theta

U - initial angular velocity

V - angular velocity

A - angular acceleration

T - Time

Symbols on data booklet, like the kinematics formulas.

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Power is the rate of change of energy transfer.

Power can be found in electricity, kinematics, ect. For example in electricity, Work done = force X distance costheta. If we differenciate this we can find power (f is a constant). So this will become Fsintheta V. Example question --> below

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A blackbody is the best absorber and emitter, taking in all the energy that hits it and giving off as much as possible. This links emission and absorption work, which is important for greenhouse effect. It’s also connected to luminosity, the total energy something gives off each second, which helps in understanding both space and climate science.

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His law states luminosity = forumla above. This can link to power as it is the "rate of change in energy transfered". This formula could be modified to include emissivity which ranges from 0-1 (blackbody surfaces), it modifies it by adding the emissivity symbol at the front of the equation. The stefan boltzmaan law says that the hotter something is, the more energy it gives off. It’s a way of understanding how much heat and light objects like stars or even the Earth give out based on their temperature.

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having only magnitude, not direction.

Examples:

Time

Voltage

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Has both magnitude and direction

Examples:

Current

Displacement

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Distance is the total length of the path traveled, regardless of direction, while displacement is the change in position from the starting point to the end point, including direction.

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When we have a current going through we will have an induced magnetic field (black line). Using faradays law, this explains the working. The current from the battery will induce the B field inside the solenoid. This than induced the current hence inducing a secondary field AKA the blue line around the solenoid.

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hard to anwser because I got confused with the clockwise and anticlockwise current.

How to solve:

Induced current opposes the change in flux.

Magnetic field direction goes into the page

Increasing → induced field out of page

Decreasing → induced field into page

Anwser: C

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Things to note:

Magnetic field is only in a small region, not whole circuit

Solving notes

Only wire segment in changing field gets induced emf (IMPORTANT REMEMBER)

Anwser: B

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Two forces at once, force on magnet and on loop (notice this)(basic induction law, always wants to achieve equilibrium)

When solving remember:

Falling magnet → changing magnetic flux → induced current creates opposing force to reach equilibrium

Equal and opposite force on loop

Anwser: B

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Remember Newton’s 3rd law

force on magnet = opposite force on loop.

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Combine Lenz’s Law with Left Hand Rule.

Apply left-hand rule so the force moves the rod to the right

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Question from Teacher Joshua: changes during refraction

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Question from Teacher Joshua: changes during refraction

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When light passes across a boundary into water or glass in undergoes refraction. Refraction doesn’t change the colour of light, but its wavelength does change during refraction.

Explain how is this possible.

Hint: 1. What stays constant during refraction and what changes?

2. Think about topic E1 atomic physics and the cause of colour.

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Important Graph 1: Draw the graph for magnitude of the electric field strength (E) vs distance (r)

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Important Graph 1: Draw the graph for magnitude of the electric field strength (E) vs distance (r)

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Important Graph 2: Draw the graph for magnitude of the electric field strength (E) vs distance (r)

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Important Graph 2: Draw the graph for magnitude of the electric field strength (E) vs distance (r)

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Power dissipated in a cell. Remember V=IR when resistance OUTSIDE the cell increases the pD also increases proportionally. Power dissipated in a cell always decreases REMEMBER.

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1. Voltmeters must be connected in parallel, so that it will find the potential difference across it. Ammeters must be connected in series circuits, because you want it to measure the current flowing through it

1. Ideal voltmeter, means that there is infinite resistance meaning that no current will be lost

2. A real voltmeter has hight resistance but not infinite meaning that some current will be lost

3. Ideal Ammeter, means that there is 0 resistance so no so it wont affect the circuit

4. Real ammeter has low resistance but never 0, so this will affect the circuit slightly.

3. Chat GPT

1. Voltmeter: Inside, it measures the potential difference between two points using a high-resistance galvanometer. The high resistance ensures that only a tiny current flows into the voltmeter, preventing disturbance to the circuit.

2. Ammeter: Inside, it uses a very low-resistance shunt (parallel resistor) connected to a galvanometer. Most of the current flows through the shunt, and the galvanometer only detects a proportional small current. This allows measurement of the total current without adding significant resistance to the circuit.

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Thermodynamic graph + carnot cycle + key terms

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Thermodynamic graph + carnot cycle + key terms

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Also note: Heat travels to cold

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It is not simple addition. The distractor option is option D because it is simple. You simply just add the both values. However this is not true for this kind of questions because that method does not apply when the speed is close to the speed of light. Hence we use the formula U'=u-v/1-uv/c

This formula is used because U' is the velocity of the same body in the original frame of reference. let U is speed of x and V = speed of Y. Direction also matters. So the anwser is 0.81c which is option C

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Resistor Q and P are connected in series. So assume each resistor is = 100, this would mean P+Q total R = 200. R is connected in parallel so when R is account for the totla resistence will not =0. This means that R has to be infinite because if a resistor is infinite it means that it will become something like an open switch. So if R has an open switch behaviour the circuit becomes a series ( Q and P only). This means that Q+P = 200, and assume each is 100 so 100+100=200.

Anwser: B

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Potential difference = V

Resistance = R

Current = I

Firstly use emf formula e=IR since r is negligible. Since this is a series just add resistance so it = 40. so 12=40I, find I than sub into the formula V=IR, than solve for V which will be 7.5V.

Anwser: D

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Understand that the definition of emf is the energy transferred by the battery per unit charge passing through it. So this can be represented by the formula

emf= energy transfered / charge

For this question 26:

The answer is B. The distractor option is D because its saying that the emf of the batter is the energy transfered in the batter minus the resistor /Q. This distracts you as you think that by doing this you will find the emf for the battery only. However the energy transfer in the resistor does not affect the battery. So the answer is B

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Work done ON the gas means that there will be an decrease in the volume, meaning that the only option is option B line PQ.

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Key words

Isochoric (isovolumetric): Volume is constant, so no work is done W=0.

Isobaric: Pressure is constant, volume changes, so work is done P=0.

Isothermal: Temperature is constant, so internal energy does not change U=0.

Adiabatic: No heat transfer Q=0.

We can use the formula Q=U+W and the goal is to not let the equation = 0, hence the only option that does not affect this is option B.

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When should I use a change in time t' vs a Lorentz transformation time co-ordinate 

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When should I use a change in time t' vs a Lorentz transformation time co-ordinate 

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Write after class....

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In a beta minus decay:

A neutron inside a nucleus decays into a proton

This process emits an electron and an electron antineutrino

At the quark level, a down quark (d) changes into an up quark (u) by emitting a boson

The boson then decays into an electron and an electron antineutrino

Sooooo

The initial quark should be a down quark

The final quark should be an up quark

The emitted boson should be W-

The boson decays into an electron and an electron antineutrino

So the answer is D

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I am unsure on how to approach this question. And in an exam say I dont know what a baryon is, how can I try eliminating options?

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Simple Harmonic Motion is a motion where the force and acceleration are proportional to and opposite in direction from the displacement from its equilibrium position

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12d is straight forward the answer is 0.4ms-1

but the issue i need help with is determining if this collision is inelastic. I don't understand what factors contribute to a collisions inelasticity.