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# Edexcel Physics Unit 2 "Physics at work" June 2013 Watch

• View Poll Results: The last question - Does resistance increase or decrease?
It increases ( using V=IR or some other method)
70.73%
It decreases using the 'lattice vibrations' theory
29.27%

1. (Original post by gideonv)
Hi guys Did anyone get the same answer as me for the 4.3ev resonant frequency question? I did......... E=hf. 4.3x 1.6 x10^-19=6.63x10^-34f so when rearranging this, f=1 x10^15
I got that!

Let me know if you disagree.

1)D
2)D
3)D
4)B (as said by others)
5) no question
6)C
7)B
8)A
9)A
10)A
3. (Original post by ALevel96)

Let me know if you disagree.

1)D
2)D
3)D
4)B (as said by others)
5) no question
6)C
7)B
8)A
9)A
10)A
is question 7 about the wire with length l and the answers were in terms of drift velocity?
i remember getting v/2 .. i think it was B ?
4. 7 is the radiation flux question
5. (Original post by ALevel96)
7 is the radiation flux question
Do you have the list of questions and their answers? if so then i'd greatly appreciate it if you post the list?
6. (Original post by Alexsk)
Guys isn't 57-60 very high for an A? The answer was V/2, and has nothing to do with charge carriers. Also, can somebody give a definition to critical angle? For the question about wavelength I did not write about troughs or peaks and just said its the distance travelled by a wave for a complete oscillation to take place. Is that correct?
Critical angle is the angle of incidence at which angle of refraction=90*, so light travels along medium boundary.
7. (Original post by x0x)
Do you have the list of questions and their answers? if so then i'd greatly appreciate it if you post the list?
Someone kindly posted them here. https://www.dropbox.com/sh/v6ydqbfrg...R-r9ZOSH?lst#/
As for the answers I guess we just work them out ourselves
8. (Original post by x0x)
Do you have the list of questions and their answers? if so then i'd greatly appreciate it if you post the list?
https://www.dropbox.com/sh/v6ydqbfrg...ZWR-r9ZOSH?lst

Another user posted ^
9. (Original post by hamzeh h)
im thinking 58-59
Way too high. 54 or 56 max.

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10. (Original post by ALevel96)

Let me know if you disagree.

1)D
2)D
3)D
4)B (as said by others)
5) no question
6)C
7)B
8)A
9)A
10)A
I disagree with 10, I got D. But either could be correct. Your thoughts?

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11. For question 4 wouldn't it be 2v?
Because v=I/nq2A because the area is doubled. Bring the 2 over and be 2v? Or am I completely wrong?
12. (Original post by x0x)
is question 7 about the wire with length l and the answers were in terms of drift velocity?
i remember getting v/2 .. i think it was B ?
Yes! all of my MC answers match yours
i forgot what question 5 was :P
13. I wrote that 3 is C. Is that wrong?
14. (Original post by B-Stacks)
For question 4 wouldn't it be 2v?
Because v=I/nq2A because the area is doubled. Bring the 2 over and be 2v? Or am I completely wrong?
You need to consider two equations here
Resistivity and the drift velocity equation
from the resistivity one you can tell that nothing changes as l and A are both doubled so they cancel out. That means that I is constant as R is unchanged
then you use I=nAvq . A is doubled but there is no l so it has to be v/2
I don't think i explained it well at all but i think v/2 is the answer. If anyone can explain this better please do so
15. (Original post by Alexsk)
I wrote that 3 is C. Is that wrong?
If you look at where the waves finish you will see that Y is ahead of X.
16. (Original post by Jaydude)
I disagree with 10, I got D. But either could be correct. Your thoughts?

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Superposition produces an interference pattern
17. 5 was the Doppler question and I think I chose C
18. (Original post by ALevel96)
5 was the Doppler question and I think I chose C
so S was moving towards O and O was moving towards s?
is that choice C? i that is the one i have chosen
19. (Original post by Alexsk)
I wrote that 3 is C. Is that wrong?
I put C too. I think we're right, because I remembered seeing this in the textbook

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20. Did anyone see through the trick question in question 17? It wasn't a negative gradient graph, because that's when the voltmeter is measuring the load resistance, but in this question the voltmeter was measuring the Pd at the battery, so it would've been a positive graph

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