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AQA PHYA4 ~ 13th June 2013 ~ A2 Physics

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ohh. crap.. on my calculator it says 30000volts.. but dunno what i put in the paper..
i couldnt do the last page... what was the maxium indueced emf 0.555-0.555/40 seconds
or o.55/40

Reply 561

shewhomustnotbnamd

Original post by Elton

That's a relief, I ended up spending too much time on that one. I'm pretty sure I got the wrong value for emf as well now I come to think of it, got something like 94V then got 1.7T for the last question :redface:

Really glad this is out of the way now and I can concentrate on Unit 5 and C4 which should be easier.

i got 94V ! :biggrin:

what did people get for the multiple choice one where they put two springs in instead of 1, i got T/root2 ? and the gravitational potential of mars? and what about the timing one before the brightness one? i said the timing would increase?

Reply 562

cooldudeman

Original post by HJFelton

What were people getting for the last question on the back? Think it'll probably be a range for you to get the marks as you had to use a gradient to calculate maximum emf (I got 100V). General thoughts of the whole thing?

I got 102. Thank god. Im pretty sure we are both right

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Reply 563

oli_G

Original post by HJFelton

You wouldn't HAVE to find the gradient surely as you know Vmax is BANw, unless they explicitly said to that (I can't remember)

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Reply 564

Alpengold

Original post by oli_G

Got 38s
1.9(x+1)=2x [x is the no. Of oscillations, the first does one more as it has a shorter T]
x=19
Therefore time =1.9(20) [or 2(19)]= 38s

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This question was previously on a multiple choice question, and answer was 38 cycles, which is what you got but the question this time asked for time taken for them to be in phase, does it not mean that you times 38 by 1.9? I might be totally wrong so if I am can you please explain it to me?

Reply 565

oli_G

Original post by shewhomustnotbnamd

i got 94V ! :biggrin:

I got 94, but I got T*root 2 (as k goes to 0.5k)

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Reply 566

shewhomustnotbnamd

Original post by oli_G

I got 94, but I got T*root 2 (as k goes to 0.5k)

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oh i thought k went to 2k :s-smilie:

oh well

Reply 567

saba146

section a: kgms-2, t root2 energy one i got 2E? ...

1a)define shm:
acceleration is proportinal to displacement, and acceleration acts toward equilibrium (2)
b)acceleration of pendulum = 0.503 3s.f (3)
c)frequency= 1500 revs per minute (2)
d) time for oscilations to be in phase again = 38 (3)

2) voltage = 30,000 (1)
b) (3)
c) time taken for discharge will increase because time constant increases (2)
d) flash is brighter because more energy stored (2)

3) 6 marker on fields?

4) 2 conditions when no force is exerted on the partcle (2)
field is parallel to velocity
particle is stationary
b)
c)time taken for partile to go through 1 dee
d)show the time taken is independent of radius = 2pim/bq (3)
kinetic energy im MEV = 2.44 (3)

angle for max emf = (2)
gradient of graph = emf (1)

drawing a graph (2)
peak voltage (3)
calculate flux density = 0.26 (2)

(edited 10 years ago)

Reply 568

PatrickM

Right... time to see how bad I've done!

*reads through thread*

Reply 569

cooldudeman

Original post by oli_G

I got 94, but I got T*root 2 (as k goes to 0.5k)

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I got Troot2 aswell. And the peak emf one, it depends on the time too so it would make sense if it was gradient

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Reply 570

Elton

Original post by YThursday

Yeah Unit 4 Physics is (was xD) my hardest exam. I had C4 (OCR MEI) this morning aswell and it was a hard paper! I've just got two more too - Unit 5 and a C3 resit :tongue:

Good luck

The only part I'm not looking forward to in Unit 5 is medical physics, our teacher chose the topic for us and I'm not as confident with it compared to if we had chosen Applied physics :frown:

Original post by shewhomustnotbnamd

i got 94V ! :biggrin:

Did you get it by finding the gradient in the graph? I forgot to draw the gradient triangle though though :s-smilie:

Reply 571

PatrickM

How did this compare to previous exams do we think? What's your opinion?

Personally I thought it was absolutely standard. Not hard, not easy either. Hopefully it went better than January for people :smile:

Reply 572

The H

Original post by YThursday

I quite liked that paper, some of it was thought provoking.

I wasn't a fan of question 5 though. Did anyone else get 14v (rounded from 13.75) for the peak voltage? Was it 1500 revolutions per minute?

Bring on unit 5! :rolleyes:

I got 1500 rpm :smile:

there's hope after all

Reply 573

oli_G

Original post by saba146

1a)define shm:
acceleration is proportinal to displacement, and acceleration actstoward equilibrium
b)acceleration of pendulum ..
c)frequency= 1500 revs per minute
d) time for oscilations to be in phase again = 38

2) voltage = 30,000 (1)
b)
c) time taken for discharge will increase because time constant increases (2)
d) flash is brighter because more energy stored (2)

3) 6 marker on fields?

4) 2 conditions when no force is exerted on the partcle (2)
field is parallel to velocity
particle is stationary
b)
c)time taken for partile to go through 1 dee
d)show the time taken is independent of radius = 2pim/bq (3)
kinetic energy im MEV = 2.44

2 marks for drawing a graph
calculate flux density = 0.26

I agree except for 4)d as its a semicircle so time taken =pim/bq

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Reply 574

shewhomustnotbnamd

Did you get it by finding the gradient in the graph? I forgot to draw the gradient triangle though though :s-smilie:

yeah i did it through finding the gradient...i actually think i got 92 though now...im sure there will be a range...but if you used values from the graph it will be obvious :smile:

Reply 575

oli_G

Original post by Alpengold

The multiple choice question had different values and it asked for the number of oscillations not time, so it's just coincidental hat the numbers match :smile:

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