You are Here: Home >< Physics

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

1. (Original post by Alexie56)
Surely if they were charged with the same voltage the initial current should be the same. They were juat discharged through different resistors. So I drew a shallower graph?😕
No V=IR so I=V/R is proportional to R since V is constant. R increases so 1/R decreases, hence I is smaller.
2. (Original post by kevincarreira)
First one is weight
June 11 paper

Posted from TSR Mobile
3. (Original post by Alexie56)
Surely if they were charged with the same voltage the initial current should be the same. They were juat discharged through different resistors. So I drew a shallower graph?😕
thought of V=IR, so initial current would be less
4. (Original post by NEWT0N)
There were 3? Hm, maybe they would want you to extend the graph to cover the whole length of the x-axis or something. Or they would not want it to intercept the x-axis but only tend asymptotically to it. I don't know
Yeah I thought so?

Erm yeah that would be likely, if they have really made a typo they might just omit the question though...

How was the rest of the paper for you?

Posted from TSR Mobile
5. (Original post by Disney0702)
75
Thanks, are the grade boundaries usually that low? (I don't check them)
6. Why did I get around 31nC for the charge?? I found the gradient and multiplied by the constant
7. (Original post by QueNNch)
Thanks for putting them!

I think you question 17 is incorrect because the question asked for the number on electrons on the NEGATIVE plate ONLY. Therefore the answer is half of what you got. (something like 2.2 x 10^10)

Posted from TSR Mobile
Q 22 i got 1/root 2
8. (Original post by Fvthoms)
55 for A*
50 for A
etc...
Hmmm just out of curiosity why'd ya 55 for A*?

Last it was 61/75 do you think this exam was significantly harder than last year.

Coz i dont know if i found harder than last year after reading peoples comments
9. I thought the same, and also, the capacitance is the same. I started mine at the same current level and ended it above the other graph.

(Original post by Alexie56)
Surely if they were charged with the same voltage the initial current should be the same. They were juat discharged through different resistors. So I drew a shallower graph?😕
10. (Original post by NEWT0N)
No time period isn't affected because it only depends on the length of the spring and a simple pendulum is isochronus.

I put the time period stays the same and there is a larger restoring force because the weight is greater at maximum amplitude so the horizontal compoent of weight (restoring force) is larger. But then I went on to say something silly like how this causes a smaller amplitude, but I think it should be a bigger amplitude? My thinking is still a bit cloudy after the exam so I'm hoping someone can clarify this for me!
I also wrote about a larger restoring force, hence a larger energy loss due to resistive forces, which would result in heavier damping. Don't know if it's correct or not...
11. (Original post by NEWT0N)
No V=IR so I=V/R is proportional to R since V is constant. R increases so 1/R decreases, hence I is smaller.
They were charged through the same circuit in the exact same way though I think so the initial current is the same. When it discharges it goes through a different circuit with the resistor. Not entirely sure though
12. (Original post by DannySmith420)
Q 22 i got 1/root 2
Same!
13. (Original post by Mehrdad jafari)
Here are my answers. The ones I'm not sure with i have mentioned next to them.

I have failed to take the answer of one of the MC questions. Let me know if you found which one.
I would be very happy if you could correct the ones that are not right
Attachment 425411

Posted from TSR Mobile
1. Is newtons as rate of change of momentum is force (newtons 2nd law)
21. I put A as it had the longest side perpendicular to the magnetic field. Its a couple and not looking for flux (so largest area is irrelevant) force on couple is F=BIl so biggest couple was A as it had largest length perpendicular to field
22. I think is 1/root 2 as kinetic energy is proportional to the square of velocity
14. anyone else get like DDDAAA near the end?
15. (Original post by Will177)
They were charged through the same circuit in the exact same way though I think so the initial current is the same. When it discharges it goes through a different circuit with the resistor. Not entirely sure though
The graph was for discharing, so my analysis applies there

V is the same as before
R for the discharing circuit is higher

Therefore V=IR for the discharing circuit gives I proportional to 1/R, so I for the discharing circuit is smaller as claimed

I reckon
51 for A
57 for A*
17. On 2nd law points I talked about how ma is mv^2/r due to v^2/r being the centripetal acceleration
18. (Original post by NEWT0N)
It went well but I was disappointed at the sheer number of repeats from previous papers which probably gave people who did lots of past papers (including me) a slight advantage on time taken to complete the paper.
Yeah the multiple choice certainly felt quite familiar! Ah well long time to wait to find out how we acc did, good luck!

Posted from TSR Mobile
19. (Original post by QueNNch)
Alright guys I drew my graph like this

Attachment 425409

I think in probably wrong because the initial current (y axis) would be lower.

Thoughts?
Totally wrong as gradient should also be shallower due to higher RC. Don't think they'll include the question though as it was worded incorrectly should have been 300ohm not 300kohm
20. (Original post by NEWT0N)
Thanks, are the grade boundaries usually that low? (I don't check them)
At the beginning of the spec the grade boundaries were pretty low. You could lose 12 marks and get full UMS.

But last year its gone up a bit.

It was 61/75 for an A* and 69/75 to get full UMS.

TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Updated: February 22, 2016
Today on TSR

### The most controversial member on TSR?

Who do you think it is...

### Uni strikes! How do they affect you?

Discussions on TSR

• Latest
Poll
Useful resources

Can you help? Study help unanswered threadsStudy Help rules and posting guidelinesLaTex guide for writing equations on TSR

## Groups associated with this forum:

View associated groups
Discussions on TSR

• Latest

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE