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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. Hi,

Why is it D and not C?

2. And here, i dont understand how to do all of the question.
3. http://www.edexcel.com/migrationdocu...e_20090115.pdf
jan09 paper
22bii) and iii)
thankyou :c
4. (Original post by JoshThomas)
If you think of it like this, brightness of bulb depends on power, power is given by i^2 r, if I is the same for both as in series therefore the brighter bulb must have more resistance, and part b) the same potential difference occurs in both branches the only difference is current and resistance of the lamps, as current takes route of least resistance, so the one with least resistance will shine brighter as p=vi, and as v is equal, a larger I, will cause a larger power, more brighter, from part a, its established that a has less resistance, so A will shine brighter in paralell, hope this helps

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thankyou so much! you're a star:]
5. We also need to be able to describe how to obtain current voltage characteristics Graphs

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6. are you guys all doing past papers at the moment? finished the book? btw which books do you guys use?
7. Please help with jan 2012 question 14)b

Please explain part b of the question.

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8. guys can someone plz send me a post of the jan 2013 unit 2 paper now please , i really need it now ,,,, thanks
9. godd!!!my mind is already blowing off even when i think abt dis exam...anyways thnQ for creating dis thread.
I wud be glad if anyone cud explain how to investigate and explain how to measure therotation of the plane of polarisation?????
10. Got stuck on another question; question 5 on multiple choice one

http://www.edexcel.com/migrationdocu...e_20100118.pdf

Unsure how the answer is 50Hz...Can someone explain?
Thanks!

EDIT! Never mind I got it. I misread "ms" (milliseconds) for meters/second.
11. (Original post by Jaydude)
Got stuck on another question; question 5 on multiple choice one

http://www.edexcel.com/migrationdocu...e_20100118.pdf

Unsure how the answer is 50Hz...Can someone explain?
Thanks!

EDIT! Never mind I got it. I misread "ms" (milliseconds) for meters/second.
4 squares, each 5ms (5x10^-3) so 4*(5x10^-3) =0.02
using formula F=1/T : 1/0.02 which is 50Hz
12. (Original post by KBenzema)
Hi,

Why is it D and not C?

The frequency of the WAVES decrease not the frequency of the siren
13. (Original post by blacknightking)
Please help with jan 2012 question 14)b

Please explain part b of the question.

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First, you need to find the current.

The p.d. across V1 is 4 V, and the resistance is 10 megaohms.

So,

We know that current is the same throughout the circuit, and the overall voltage is 6 V, so the total resistance would be:

The total resistance of the circuit would be found by adding up the resistance of V1 and the other voltmeter and the resistor that are in parallel.

So,

Solve for R.
14. Hi, can someone please help with me this question on power.

Its Question 15bii) on the June 2010 paper, I've linked the question below:

http://www.edexcel.com/migrationdocu...e_20100609.pdf

Can someone please explain what it means by the following points, i just don't understand

Heres what is says on the mark scheme:

See internal resistance / r (1)
Current will be less (1)
Less energy/power is lost in internal resistance OR wasted
energy/power is reduced OR reduced lost volts OR it is more efficient (1)

Thanks

15. Hi, can someone please help me with this question on power.

Its question 15bii) from the June 2010 paper:

http://www.edexcel.com/migrationdocu...e_20100609.pdf

Can someone please explain on the points from the markscheme, i just don't understand what they mean when relating to the question itself (on time etc.) .

Here is a copy of the points on the markscheme:

QWC – spelling of technical terms must be correct and the answer
must be organised in a logical sequence
See internal resistance / r (1)
Current will be less (1)
Less energy/power is lost in internal resistance OR wasted
energy/power is reduced OR reduced lost volts OR it is more efficient (1)

Thanks

16. Guys I was wondering so what actually is charge. I understand that in a circuit there is a flow of current and that current is a flow of electric charge, but what actually is charge I'm finding it hard to understand
17. (Original post by sarah.102)
Guys I was wondering so what actually is charge. I understand that in a circuit there is a flow of current and that current is a flow of electric charge, but what actually is charge I'm finding it hard to understand
Just think of charge as a load of electrons flowing around in a wire, just lots of negative species.
18. http://www.edexcel.com/migrationdocu...e_20110117.pdf
question 2?:c
it's just a multiple choice question, but i dont get it
19. Also guys, latest confusion what is potential difference? I understand that it is the measure of energy transfer in between 2 points in an electric circuit or it drives the circuit by forcing the current to flow but still I feel a bit confused. Say if I calculate the potential difference and get 3V what does that actually mean?
20. (Original post by GCSE-help)
Just think of charge as a load of electrons flowing around in a wire, just lots of negative species.
Thanks that makes sense. I have a new question about potential difference which I just posted if you can please answer, I'll be very much grateful

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