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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 ambbs)
Jan 2012, q7. The answer is A but I don't get why! Thanks in advance Attachment 221933
Someone explained this a few pages ago. Have a lil search.
2. (Original post by B-Stacks)
Someone explained this a few pages ago. Have a lil search.
Ah okay, thanks - found it now, must have missed it before
3. (Original post by StUdEnTIGCSE)
That's in A2.

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Coool

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4. (Original post by LegendX)
Anyone know how I would work out the reading on the voltmeter?
Anyone?
5. (Original post by Branny101)
Coool

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But the statement
"The wavelength of an electron is almost equal to the atomic size or spacing" is very important!
6. (Original post by wirralriddler)
I got a little confused by this question when I did this paper too :/
It was explained to me like this: Basically assuming P.d stays constant and that V=IR you know that the general shape must have a -ve gradient because as I increases, R must decrease (so that V stays the same). The fact that it's a curve and not a straight line is to do with the fact that the current causes the resistor to heat up (I think, so the 'kept at constant temp' thing must be referring to the external conditions only) and given that increased temperature causes resistance to increase (in metals/decrease in other semiconductors), the resistance/current relationship wouldn't be linear. Quite a misleading question in my opinion!
Im sorry to say but I think that explanation is plain nonsense.

V=IR
I=V/R
v is constant so I=k/R

Now wont a AS student feel ashamed when they do not know how to sketch a y=k/x
curve???????
Weren't we supposed to learn the curve shape in GCSE itself???
7. i gave up on physics in jan! so i have to try and teach myself this unit in a couple of days! i wont start the revision till after my exam tomorrow! if anyone can give me some tips and handy ways of remember key terms and equations i would be very grateful!
8. (Original post by wirralriddler)
P.d across branches in parallel with the power supply are always equal to the voltage across the power supply I think. So the answer would just be 15v?
It was not 15V, the answer was 12V
9. (Original post by StUdEnTIGCSE)
Im sorry to say but I think that explanation is plain nonsense.

V=IR
I=V/R
v is constant so I=k/R

Now wont a AS student feel ashamed when they do not know how to sketch a y=k/x
curve???????
Weren't we supposed to learn the curve shape in GCSE itself???
It happens man, the recognition of graph shapes aren't always something that comes straight to mind when seeing that equation.

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10. (Original post by syders123)
i gave up on physics in jan! so i have to try and teach myself this unit in a couple of days! i wont start the revision till after my exam tomorrow! if anyone can give me some tips and handy ways of remember key terms and equations i would be very grateful!
Good luck.
11. (Original post by wirralriddler)
Alright chill out... just a messy way of explaining it I guess. Sorry! Just how it was explained by my teacher... cheers
Lol!

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12. (Original post by StUdEnTIGCSE)
Im sorry to say but I think that explanation is plain nonsense.

V=IR
I=V/R
v is constant so I=k/R

Now wont a AS student feel ashamed when they do not know how to sketch a y=k/x
curve???????
Weren't we supposed to learn the curve shape in GCSE itself???
The exam stress has gone to his mind, he's going crazy.
13. (Original post by LegendX)
The exam stress has gone to his mind, he's going crazy.
Nope, I'm not stressed out.

But giving explanations like that just makes you roflyao ...

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14. (Original post by LegendX)
The exam stress has gone to his mind, he's going crazy.
Legend, did you find the answer to your question? I'm also interested .

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15. I just have a feeling that the grade boundaries for this series is going to be really high ... we have got some really bright candidates here :P
So the best way to revise is to do all the past papers and all the extra exam questions I can find,eh?
16. (Original post by x0x)
I just have a feeling that the grade boundaries for this series is going to be really high ... we have got some really bright candidates here :P
So the best way to revise is to do all the past papers and all the extra exam questions I can find,eh?
And old spec questions
17. (Original post by Branny101)
Legend, did you find the answer to your question? I'm also interested .

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Nope, still haven't and the funny thing is that because it's one mark its prob really simple >M
18. (Original post by x0x)
I just have a feeling that the grade boundaries for this series is going to be really high ... we have got some really bright candidates here :P
So the best way to revise is to do all the past papers and all the extra exam questions I can find,eh?
A few bright people on TSR does not represent the country lol, don't worry.
19. (Original post by legendx)
anyone know how i would work out the reading on the voltmeter?
someone must know how to do this question? Click on the original post link to see the question. Someone? Anyone?
20. could someone please explain to me why the answer to this question is A? thank you

ignore this I've just realised it's on this thread
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