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# AS Physics: Current and Charge (I=nAVq) watch

1. Question
A current of 0.6A flows in a wire with 5 x 10^28 free electrons per unit volume. If the drift velocity of these electrons is 8.0 x 10^-4 m/s, calculate the diameter of the wire.

So i'm using I = nAVq

Am i right in saying:

Amps

m^3

m/s

what is q?
2. q = charge on an electron

the equation is sometimes written I = nave (swap e for q) when electrons are involved
3. q = charge in C carried by each charge carrier
4. so in terms of my question q or e whatever.. will be:
(5 x 10^28) x (1.6 x 10^-19) ??
5. (Original post by neomilan)
so in terms of my question q or e whatever.. will be:
(5 x 10^28) x (1.6 x 10^-19) ??
6. (Original post by EierVonSatan)
are my I n and V correct though?
7. (Original post by neomilan)
are my I n and V correct though?
I, n and v look good
8. (Original post by EierVonSatan)
I, n and v look good
ah ok good

i get 1.875 x 10^-36 m^2 for my A

hopefully thats correct and then i'll just divide by pi and square root it and then times by 2 to get my diameter
9. (Original post by EierVonSatan)
I, n and v look good
One more question: if charge passing a pair of headlamps are 6000 each and charge passing a pair of side lamps are 600 each
will the charge in passing the battery be 6000+6000+600+600 ?
10. (Original post by neomilan)
One more question: if charge passing a pair of headlamps are 6000 each and charge passing a pair of side lamps are 600 each
will the charge in passing the battery be 6000+6000+600+600 ?
Yeah, the total charge in a system is the sum of all the smaller charges
11. thanks! -- i have another question --> http://www.thestudentroom.co.uk/show...php?p=15342283

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