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AQA Physics PHYA4 - Thursday 11th June 2015 [Exam Discussion Thread] watch

1. (Original post by AR_95)
yes

I said what you did but I realise its wrong

light damping has no effect on the time period because Amplitude is not related to time period, but with damping the amplitude generally increases

heavier damping should be with the ring on i think
I thought it would be more dampened with the ring off because the air resistance would be the dampening force, and with no ring the air resistance would have had a greater effect than with the ring on?
2. (Original post by Alexie56)
Don't you get 4mJ from the battery and then minus 2mj to get the energy used up which is 2. So B couldn't havw been incorrect.
So, everyone agrees A was right (as in correct so this was not the answer) Between BCE. if C was wrong then so was D and vice versa (there were only two components not including the cell) So B was left
3. (Original post by AR_95)
yes

I said what you did but I realise its wrong

light damping has no effect on the time period because Amplitude is not related to time period, but with damping the amplitude generally increases

heavier damping should be with the ring on i think
Less damping 100% certain. Just imagine swinging a pice of paper from a pendulum & a mass from a pendulum, which takes longer to stop?...
4. (Original post by smoothER)
Same, and I know two others who got this
I got it too
5. (Original post by TheRAG)
So the answer should have been weight?
indeed

Weight is a force so has unit N

or

Weight = mg = Kg ms-2 which is another unit of force
6. (Original post by chizz1889)
First question 10000% was weight, by laws of dimensional analysis 😋
Oh yeah, you're right. I was confused that a=ma haha

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7. (Original post by k9000)
So, everyone agrees A was right (as in correct so this was not the answer) Between BCE. if C was wrong then so was D and vice versa (there were only two components not including the cell) So B was left
Nope B is wrong as some energy is used to oppose resistance in the circuit
8. (Original post by TheRAG)
For the coil with a power supply and ammeter, which way should the needle have initially gone? And which way should it have gone in the next part?
I explained using lens's law and faradays law, did anyone else do this?
Yeah I said the needle would initially go in one direction and then in the opposite direction because of Lenzs law

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9. (Original post by NEWT0N)
Whichever one had the largest area. I remember it being a square with side length 0.5. If that one was option B then yes, B is correct.
Was the area 0.25 then? Cause I definitely remember that as the largest
10. (Original post by Humbers)
It isn't acceleration the guy you quoted got it wrong. You are right rate of change of momentum is force which has the unit Newtons
So did you put weight as the answer?
11. Anyone remember what they got for the work done to move the 60nC charge?
12. (Original post by chizz1889)
Nope B is wrong as some energy is used to oppose resistance in the circuit
Yeah b was incorrect that's what i'm saying
13. (Original post by TheRAG)
For the coil with a power supply and ammeter, which way should the needle have initially gone? And which way should it have gone in the next part?
I explained using lens's law and faradays law, did anyone else do this?
Were we given enough information to determine which way the needle went? (Can't remember now, but if there was a galvanometer on coil P then yes)

All I remember writing is that the needle shows a flick, because when the switch is closed a current flows through coil P, so a magnetic field grows around it and passes through coil Q. The change in flux through Q thus induces an emf through it, and since the circuit is complete an induced current flows.
14. (Original post by huniibehi)
Yeah I said the needle would initially go in one direction and then in the opposite direction because of Lenzs law

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The second bit was just less deflection

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15. (Original post by TheRAG)
Was the area 0.25 then? Cause I definitely remember that as the largest
I think it was B
16. (Original post by TheRAG)
Was the area 0.25 then? Cause I definitely remember that as the largest
It was definitely the largest. They were 0.2, 0.25, 0.16, 0.15 or something.
17. (Original post by Fvthoms)
10000% was not. 😂
Yes it is. Rate of change of momentum is MLT ^-1 * L^-1 = MLT^-2
Weight is M * LT^-2 which also = MLT^-2
18. (Original post by joesterman)
Anyone remember what they got for the work done to move the 60nC charge?
4.5x10 to something
19. (Original post by Alexie56)
Don't you get 4mJ from the battery and then minus 2mj to get the energy used up which is 2. So B couldn't havw been incorrect.
Yeah i thought this, half goes to capacitor half goes to resistor?
20. (Original post by huniibehi)
Yeah I said the needle would initially go in one direction and then in the opposite direction because of Lenzs law

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Did it go left first then right? Or the other way round?

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