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# AS Physics electricity equation question, help needed

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1. A current of 0.4 A flows in a copper wire with a diameter of 0.22 mm. Calculate the mean drift velocity, in m s-1, of the electrons. Using electron number density as 8.0 x 10^28.I've been trying for a while now and I need it for tomorrow, if you find the answer please state how you did it so I can see where I am going wrong, thanks in advance!
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3. Popped this in the Physics forum for you - you're more likely to get an answer here
4. (Original post by RobeTG)
A current of 0.4 A flows in a copper wire with a diameter of 0.22 mm. Calculate the mean drift velocity, in m s-1, of the electrons. Using electron number density as 8.0 x 10^28.I've been trying for a while now and I need it for tomorrow, if you find the answer please state how you did it so I can see where I am going wrong, thanks in advance!
I am afraid I don't know what is wrong with your trying. It may be good that you show your trying. Since this two days ago, I hope the following answer is useful.

The drift velocity is given by
---eqn(1)

I think the number density is given in electrons/m3.

The cross-section area A is

Plug in all the numbers into equation (1)

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