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

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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

Reply 441

Seclusion

Original post by Whizbox

Thank you! Are there any disadvantages to this method?

Reply 442

Whizbox

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

Reply 443

WillRose

is there anything else about derivations that we need to know other than that?

Reply 444

Mango Milkshake

Is the derivation on the spec?

Reply 445

rory58824

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).

Reply 446

C0balt

Original post by Mango Milkshake

Is the derivation on the spec?

Yes it says assumptions leading to and derivation of pV=1/3Nmc^2

Reply 447

duncant

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"

I feel your pain

Reply 448

Mango Milkshake

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... :shoot:

Reply 449

WillRose

Original post by duncant

>Right click
>Save Image As
>"gas shit.jpg"

I feel your pain

Reply 450

C0balt

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... :shoot:

Same here lol.
What with the hard-core alpha particle algebra in PHYA4 I wouldn't be surprised if it came up tbh

Reply 451

Mango Milkshake

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

Reply 452

rory58824

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.

Reply 453

duncant

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...?

Reply 454

Mango Milkshake

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...

Reply 455

C0balt

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

Reply 456

Yo12345

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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