AS Physics: Current and Charge (I=nAVq) Watch

neomilan
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#1
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#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:

I = 0.6 Amps

n = 5 \times 10^28 m^3

A =

V = 8 \times 10^-4 m/s

q =  ?

what is q?
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EierVonSatan
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#2
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#2
q = charge on an electron

the equation is sometimes written I = nave (swap e for q) when electrons are involved
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shyamp
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#3
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#3
q = charge in C carried by each charge carrier
0
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neomilan
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#4
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#4
so in terms of my question q or e whatever.. will be:
(5 x 10^28) x (1.6 x 10^-19) ??
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EierVonSatan
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(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) ??
:yep:
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neomilan
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(Original post by EierVonSatan)
:yep:
are my I n and V correct though?
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EierVonSatan
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(Original post by neomilan)
are my I n and V correct though?
I, n and v look good
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neomilan
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#8
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#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
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neomilan
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#9
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#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 ?
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EierVonSatan
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#10
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#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
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neomilan
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#11
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#11
thanks! -- i have another question --> http://www.thestudentroom.co.uk/show...php?p=15342283
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