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# AQA Physics PHYA5 - 28th June 2016 [Exam Discussion Thread] watch

1. (Original post by Seclusion)
Can someone explain how electron diffraction calculates the nuclear radius?
Measure electron beam intensity at various angles from the normal. Plot on a graph, find the angle of theta for where intensity is a minimum. Use equation r=0.61lambda/sin(theta) to work out r. Lambda is wavelength of the electrons
2. (Original post by Whizbox)
Measure electron beam intensity at various angles from the normal. Plot on a graph, find the angle of theta for where intensity is a minimum. Use equation r=0.61lambda/sin(theta) to work out r. Lambda is wavelength of the electrons
Thank you! Are there any disadvantages to this method?
3. (Original post by Seclusion)
Thank you! Are there any disadvantages to this method?
The electron needs to have a really short wavelength in order to diffract between the very small gaps between atoms so needs to be accelerated to a very high velocity, so needs a very large accelerating potential

4. is there anything else about derivations that we need to know other than that?
5. Is the derivation on the spec?
6. (Original post by Mango Milkshake)
Is the derivation on the spec?
Yes. I've memorized it, but my teacher has said that the assumptions are more likely to come up (don't believe a word she says).
7. (Original post by Mango Milkshake)
Is the derivation on the spec?
Yes it says assumptions leading to and derivation of pV=1/3Nmc^2
8. (Original post by WillRose)

is there anything else about derivations that we need to know other than that?
>Right click
>Save Image As
>"gas shit.jpg"

9. (Original post by rory58824)
Yes. I've memorized it, but my teacher has said that the assumptions are more likely to come up (don't believe a word she says).
(Original post by C0balt)
Yes it says assumptions leading to and derivation of pV=1/3Nmc^2
(Original post by C0balt)
Yes it says assumptions leading to and derivation of pV=1/3Nmc^2
Wow, lucky i came on here! I just skipped it because I thought that seems too complicated to come up. Will try to learn it in a few hours...
10. (Original post by duncant)
>Right click
>Save Image As
>"gas shit.jpg"

11. (Original post by Mango Milkshake)
Wow, lucky i came on here! I just skipped it because I thought that seems too complicated to come up. Will try to learn it in a few hours...
Same here lol.
What with the hard-core alpha particle algebra in PHYA4 I wouldn't be surprised if it came up tbh
12. (Original post by C0balt)
Same here lol.
What with the hard-core alpha particle algebra in PHYA4 I wouldn't be surprised if it came up tbh
Has it ever came up? I've done the new spec papers and it's not on any of them
13. (Original post by Mango Milkshake)
Has it ever came up? I've done the new spec papers and it's not on any of them
I've only seen questions on the assumptions, so it really wouldn't surprise me if it came up. However, I'm expecting a 6 marker on something with nuclear power stations OR specific heat capacity.
14. (Original post by Mango Milkshake)
Has it ever came up? I've done the new spec papers and it's not on any of them
its never come up, only assumptions you have to make. Does that make it more likely to come up this year though...?
15. (Original post by duncant)
its never come up, only assumptions you have to make. Does that make it more likely to come up this year though...?
as cobalt said, there was a hard algebraic question on phya4 (the daughter nuclear stuff) so it could...
16. (Original post by Mango Milkshake)
Has it ever came up? I've done the new spec papers and it's not on any of them
No, but in a test we did at our school there was a question on it, but it was probably from old spec papers
17. Why on Earth were the neutrons included in fission calculation in June 2011, but not in June 2014? When would I know when to include it or not?

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18. (Original post by marioman)
Experiment to detemine the specific heat capacity of a substance?

Just a random guess.
Could you explain how you would do this?

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19. (astro) quick way to convert hubble constant to age of universe. 3.08x10^19/hubbleconstant answer units are seconds
20. (Original post by Yo12345)
Could you explain how you would do this?

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http://www.chemteam.info/Thermochem/...ific-Heat.html

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