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

1. (Original post by RemainSilent)
is it 100% certain that good old AQA is gonna give those people credits who did a horizontal line form about 0 ? 3 marks for a line lol
Yes. They asked a question and that was the only correct answer.
2. 2b) the first bit is right

the 2nd mark is for
a positive test charge will have to do work against the field to reach a point in this field from infinity (or something to that effect.)
3. 2b) the first bit is right

the 2nd mark is for
a positive test charge will have to do work against the field to reach a point in this field from infinity (or something to that effect.)

also wondering why 2) e) is 1560, cant remember if i got that or nah
4. (Original post by Crash1234)
For 3B, I said the capacitor will not fully discharge, so not all the energy stored will be used, will this get a mark??
Hopefully, that was one of the reasons I gave too.
5. Could've sworn the answer to the couple question was B, the torque of a couple = Fs and B and I were constant
6. (Original post by sam_97)
Could've sworn the answer to the couple question was B, the torque of a couple = Fs and B and I were constant
It was I'm pretty sure. B was the 0.5x0.5 one.

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7. Can someone remember/verify this please? cheers

(1) 4.4*10TOTHE POWER OF SOMETHING electrons? (not halved answer)

(2) Was the 4 coils A (the one with the larger side?)

(3) was the last ques power heat loss something?

(4) was the mass on the scale definitely -322g? (many others have said 0 for some reason)

And finally for damping
Which box did you have to tick 1st or second? the ques wording was confusing me

Additonal ques, why would the height not reach 1.4 in real life ?
1) work done against air resistance
2) thermal energy lost as heat by the motor?
8. (Original post by CD223)
It was I'm pretty sure. B was the 0.5x0.5 one.

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I put A because the longer side would experience more force tand the top side would experience no force as it is parallel to to B not sure tho
9. (Original post by RemainSilent)
Can someone remember/verify this please? cheers

(1) 4.4*10TOTHE POWER OF SOMETHING electrons? (not halved answer)

(2) Was the 4 coils A (the one with the larger side?)

(3) was the last ques power heat loss something?

(4) was the mass on the scale definitely -322g? (many others have said 0 for some reason)

And finally for damping
Which box did you have to tick 1st or second? the ques wording was confusing me
1. yes, 2. no, 3. last multiple choice question? no, 4 yes

Damping was I believe the second box?
10. (Original post by CD223)
Updating MS in the first post. Any help people!?

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For the emf induced dont you multiply it by the number of turns? Because I got 4.8
11. (Original post by ssargithan)
Anyone did emf divide by square root 2?
YES. did you get 0.13A?
12. 2b) the first bit is right

the 2nd mark is for
a positive test charge will have to do work against the field to reach a point in this field from infinity (or something to that effect.)

also wondering why 2) e) is 1560, cant remember if i got that or nah
13. Lol the picture people in the picture on bbc website are surely doing maths you can see the pink formula bookleta

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14. (Original post by CD223)
Updating MS in the first post. Any help people!?

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for the raising height of 1.4m thing, in practice it wouldnt go as high because energy is lost due to air resistance of the air, plus the heating effect of the current??
15. (Original post by CD223)
Updating MS in the first post. Any help people!?

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Other possible points for 1)a):

Forced oscillations:
When a periodic force (PF) is applied to a natural oscillator (NO) (Which has a natural frequency).
If PF has frequency much lower than NO, then NO oscillates with roughly same amplitude as periodic force. Small/no phase difference.
If PF has frequency much higher than NO, then NO oscillates with small amplitude. Variable phase difference and amplitude. Max amplitude when PF is pi/2 radians out of phase with NO and minimum amplitude when PF is in phase with NO.

Also in resonance, oscillations may be violent.
16. (Original post by Lau14)
1. yes, 2. no, 3. last multiple choice question? no, 4 yes

Damping was I believe the second box?
It was -322, it's been on other past papers ☺️
Ignore that I read it wrong lol
17. Thanks!

(Original post by JizzaStanger)
Other possible points for 1)a):

Forced oscillations:
When a periodic force (PF) is applied to a natural oscillator (NO) (Which has a natural frequency).
If PF has frequency much lower than NO, then NO oscillates with roughly same amplitude as periodic force. Small/no phase difference.
If PF has frequency much higher than NO, then NO oscillates with small amplitude. Variable phase difference and amplitude. Max amplitude when PF is pi/2 radians out of phase with NO and minimum amplitude when PF is in phase with NO.

Also in resonance, oscillations may be violent.
18. Can someone explain why Q20 in section A was -322g and not zero?
19. At lowest in MC i got 20/25 and around 30-34ish on written (4 marks lost damping, 3 graph, 1 area under graph, 3 angle :/ , few more in written not sure if i lost 2 at potential ) would 50 be a B ?

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