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# OCR Physics B G495 Field and Particle Pictures June 21st 2011 Exam Thread watch

1. (Original post by Summerdays)
The anser is 4.35

For the realitivistic it was gamma = Erest + Ekinetic/Erest

gamma = 1/root(1-v^2/c^2)
I tried that! but whenever i rearranged to find v, the root was negative .. so couldn't do it, are you meant to just ignore negative or what? :s or am i completely in the wrong direction?

I ended up getting a spare piece of paper and just writing a whole load of random things i could calculate with what i had in vain hope of getting some method marks haha
2. (Original post by arianex)
800 plus 1/2? I thought it was 2d = nlambda...either way, something around the line of 500-ish nanometers for that laser?

PS// Those prep Qs were gorge. Made Section C mostly dreamy. You = hero. ^^
~500nm was what I got. using lambda = 2d/800
3. What did people put for the effects on the amplitudes of OX and OY question by removing the air?
4. (Original post by arianex)
800 plus 1/2? I thought it was 2d = nlambda...either way, something around the line of 500-ish nanometers for that laser?

PS// Those prep Qs were gorge. Made Section C mostly dreamy. You = hero. ^^
for minima isn't it nlambda/2 when n = odd number? so they interfere completely destructively and out of phase?
5. (Original post by arianex)
800 plus 1/2? I thought it was 2d = nlambda...either way, something around the line of 500-ish nanometers for that laser?

PS// Those prep Qs were gorge. Made Section C mostly dreamy. You = hero. ^^
It said MINIMUM and for a minimum path difference = (n + 1/2)lambda
But I could be wrong though, in this case. I guessed
6. (Original post by Geekchic17)
for minima isn't it nlambda/2 when n = odd number? so they interfere completely destructively and out of phase?
No it's (2n +1)lambda 2n +1 = odd
7. (Original post by Revolution is my Name)
What did people put for the effects on the amplitudes of OX and OY question by removing the air?
I made it up:

I said remove air, density decreases and thus the refrative index decreases and thus less of the light becomes referacted and thus the phase difference between the phasors become more and more out of phase.
8. got ignore anyone know the phasors one in section c? n also how to find the mass of uranium per year or anything?
9. I need to stop reading this thread lol, I can see my grade slipping away.
10. (Original post by Summerdays)
I made it up:

I said remove air, density decreases and thus the refrative index decreases and thus less of the light becomes referacted and thus the phase difference between the phasors become more and more out of phase.
wt to put in the arrow? omg i get this wrong i know
11. (Original post by Revolution is my Name)
What did people put for the effects on the amplitudes of OX and OY question by removing the air?
I said that the one related to the air would rotate.
12. (Original post by wki)
wt to put in the arrow? omg i get this wrong i know
The oppoite direction, I think
13. (Original post by Summerdays)
I made it up:

I said remove air, density decreases and thus the refrative index decreases and thus less of the light becomes referacted and thus the phase difference between the phasors become more and more out of phase.
they were completely out of phase to begin with so they couldn't get more out of phase
14. (Original post by Geekchic17)
I tried that! but whenever i rearranged to find v, the root was negative .. so couldn't do it, are you meant to just ignore negative or what? :s or am i completely in the wrong direction?

I ended up getting a spare piece of paper and just writing a whole load of random things i could calculate with what i had in vain hope of getting some method marks haha
Nah, definitely meant to get a positive root :/

What equation did you end up with after you rearranged to find V?

I think (can someone confirm this?) it was meant to be
15. (Original post by Summerdays)
The oppoite direction, I think
same here how to find the mass of uranium per year or anything?
16. (Original post by Kingbradley6)
I think that's irrelevant? But if someone could explain their logic/calculations behind this question it would be appreciated.
Hmm it probably is What I was trying to say though, is that only low-risk patients will get a scan. So low-risk patients, getting a very small amount of radiation.

Anywho, I think we've had enough confirmation on here that it's 4.35. If that's too low then blame OCR
17. (Original post by ejw93)
they were completely out of phase to begin with so they couldn't get more out of phase
wt u reckon the ans will b ? i"ve totally no idea on this one
18. (Original post by ejw93)
they were completely out of phase to begin with so they couldn't get more out of phase
They were, before the air was put in front of one of the mirrors, I think?
19. Well, it asked to comment on the amplitudes, so I said that of OX (or whichever it was where they were removing the air) would increase because less was being refracted and so more reflected, and there'd be no change for OY. Then it said to mention the detector signal, and I think I guessed at their being more minima.
20. (Original post by jimmeh)
Nah, definitely meant to get a positive root :/

What equation did you end up with after you rearranged to find V?

I think (can someone confirm this?) it was meant to be
Yes, that's what I did.

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