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

I'm getting close to 90%, but as I flopped the ISA, I need 112 on each paper so yeah not happening. The good thing is I only need a B to get an A overall

How much are you getting on mc ? I'm only getting 15/25

I'm getting close to 90%, but as I flopped the ISA, I need 112 on each paper so yeah not happening. The good thing is I only need a B to get an A overall

How much are you getting on mc ? I'm only getting 15/25

I usually make stupid mistakes on MC too. Got 15/25 in my mock and in the past papers I've done I've averaged about 15-20, always seem to make stupid mistakes on it. When I go through after there's only usually 1 or 2 that I think ahh right I really didn't know that.

June 2011 MC Question 9:

Why is the damping force always in the opposite direction to the velocity?
I always thought it was always towards the centre of the oscillations, like the acceleration, which is always $a=-\omega^{2}x$ hence the minus sign.

Is it because the force and velocity are in phase?

Also, Question 23:
Is it the rate of change of flux linkage that becomes zero but the magnetic flux linkage that remains constant when the magnet comes to rest? I got confused. I think I get it now but I wanna make sure.

Posted from TSR Mobile

What are the options? If you think about it, the damping force is logically against velocity as the damping force is acting upon the oscillating object such that it will reduce its amplitude. As it's amplitude is proportional to its max speed, reducing its max speed will reduce its amplitude and therefore the system has been damped (so, to reduce its max speed the damping force opposes the direction of speed)

Number 23, I am struggling to understand it. My instinct would be B because I think the magnetic flux linkage is the area exposed to the field or something, so as it goes inside it will increase and then become constant. If this is wrong I sound stupid but oh well.

That makes sense, thank you!

Not having a good day today. Accidentally cancelled $v$ and $V$ on both sides of the equation:

$BQv=\frac{QV}{d}$


Posted from TSR Mobile

Haha that's an easy thing to do by accident. I've been doing maths today really, I don't like differential equations at all

Ah differential equations from C4 or M2? I suppose it's the same topic either way but for some reason I find M2 ones easier haha.


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It's question 8 on C4 June 2005 that I'm struggling with. Thankfully I found out the grade boundaries were 54 for 80 ums

Oh I see! Do you understand it with the MS or would you like an explanation?


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On part B I can get to the part where you have t and c but I don't understand how to get the answer in the form V=A+Be^-kt

I tried to sub in t and c to -1/kln(20-kV)=t+c but I wasn't able to simplify that to get the answer, not sure if I just couldn't simplify it or if this is the wrong thing to do?

I've not done this question as I do AQA unfortunately so I don't have a written solution to it :/
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Oh yeah I didn't consider exam boards haha, got it explained by someone now anyway, mark scheme just over complicated it. Still pretty hard though.

Does anyone know why they omitted question 15 of the MC from January 2011 of the PHYA4 paper? Is it because it was ambiguous as to whether it was a uniform or radial electric field?


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How do you know if it was omitted?


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There was an erratum notice with the paper telling invigilators to instruct candidates to cross out the question.



Only reason I can think of is maybe because it could refer to uniform or radial fields?


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I realise this is a Unit 1 question, but I thought this was the best place to ask.
Could someone please explain how to do 2b?
https://www.dropbox.com/s/z534tiu1hkw99e0/IMG_20150513_204516.jpg?dl=0
Thanks