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# AQA Physics PHYA4 - 20th June 2016 [Exam Discussion Thread] watch

1. (Original post by Simple Harmonic)
I think what they were pertaining towards is that the electron is released at a range of speeds (it's velocity isn't constant) since some of the momentum is also taken up by the antineutrino that is also released.
I put that N only including the mass of the nucleons of the atom, and did not take into account the mass of the electrons. So, as a beta particle primarily involves an electron, m and N would be the same mass.

Does that look like an acceptable answer?
2. (Original post by liverpool2044)
ok a few questions

1, i put 11 microfarad for first part i clearly put gradient = q/v and triangle will i pick up marks
2, the question after will there be ecf for it
3, time constant i used ln0.8 how many marks lost
4, could i talk about the mass in beta minus p question and link to kinetic equation

thanks
1. Probably.
2. Probably, but only if you used the right method in the first part (which it sounds like you did).
3. No one knows.
4. No one knows.
3. (Original post by spanisholive)
Not sure if it would be worth any marks because it doesn't really show the equation being used or understanding that V=0.2Vo. Sorry
I thought it decreased to 80% of the value, so V=0.8Vo ?
4. (Original post by jonny7bell)
I thought it decreased to 80% of the value, so V=0.8Vo ?
5. (Original post by marioman)
Damn, how many marks was it out of? I am pretty sure I got the formula right so I got 202s I think.
6. Has anyone uploaded a markscheme or the question paper yet?
7. (Original post by jonny7bell)
I thought it decreased to 80% of the value, so V=0.8Vo ?
Yep it decreased by 80%. So say if the original value was 1, the new value would be 0.2.
8. is there an unofficial mark scheme to section B?
9. (Original post by BlueSi)
For the last question on section B, I thought that no current is induced in the wheel because it's not connected to a circuit? So there's a magnetic force on the wheel which causes it to slow down but no current. Does anyone know if i'm going to lose marks if I didn't talk about electromagnetic induction in that part?
exactly what i did. we're right that there is no current , but the is emf induced and i didn't mention that
10. (Original post by jonny7bell)
Damn, how many marks was it out of? I am pretty sure I got the formula right so I got 202s I think.
I dont remember how many marks it was out of. But I also accidentally used 0.8 instead of 0.2 and I got the same answer as you (202s). We wont lose that many marks for it though, since the method is correct and then there "might" be ECF for the next part.

Anyone know what was the answer to Q20 multiple choice? The one about capacitors that we had to select which option had the correct graphs for Voltage and for Current i think...
11. (Original post by KD1997)
exactly what i did. we're right that there is no current , but the is emf induced and i didn't mention that
i thought that if an emf is induced then that means the electrons experience an electromagnetic force and so move, so there is a current ?
12. What did people do for the momentum of the alpha particle?
13. (Original post by jonny7bell)
What did people do for the momentum of the alpha particle?

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14. Is there an unofficial markscheme to either paper yet? if so could someone post the link please?
15. (Original post by Waffles15)
Is there an unofficial markscheme to either paper yet? if so could someone post the link please?
There is one for both.

Section A: http://www.thestudentroom.co.uk/show....php?t=4177478

Section B: http://www.thestudentroom.co.uk/show...8#post65947098
16. kingaaran could you post the paper please
17. Did anyone else get 1e-12 kgms-1 for the momentum of the alpha particle?
18. (Original post by jonny7bell)
I put that N only including the mass of the nucleons of the atom, and did not take into account the mass of the electrons. So, as a beta particle primarily involves an electron, m and N would be the same mass.

Does that look like an acceptable answer?
Hmm, doesn't sound quite right. Why would m and N be the same mass? m is the mass of an electron (in the latter case) and N the mass of the nuclei.

I think what they are really looking for is the fact that the velocity of the electron varies; the kinetic energy of the alpha particle is, conversely, constant due to the nature of the decay.

The momentum of the electron varies since some of the momentum is shared between the electron and some by the antineutrino. The proportion that goes to each varies from decay to decay.
19. (Original post by xMillnsy)
Anybody got a summary on ligands and complex ions?
I think you're in wrong place
Unless physics Unit 4 now includes complex ions accelerating through an electric field
20. I wrote my answers to Section B ( written paper) in fountain pen :0 Will it not get scanned ?

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