Posted by **Kate** on Thursday, February 4, 2010 at 4:22pm.

How do I solve this problem:

A particular wire has a current of 10A.

A) How many electrons pass a fixed point every 5 seconds?

B)If a wire has a radius of 2 x 10^(-3) m and the electron drift speed is 2.63 x 10^(-5) m/s, determine the number density of electrons in the wire.

The teacher posts the answers for us, so the answer for

A) 3.125 x 10^(20) e^(-)

B) 1.89 x 10^(29) e^(-)/ m^3

- College Physics -
**drwls**, Thursday, February 4, 2010 at 7:42pm
It looks like you are switching names. Why?

A) Current (in Amperes) is charge passing by per second.

B) Current = (free electron number density)x (drift speed) x (cross sectional area)

Solve for the FREE electron density. (Electrons that remain attached to the nuclei of the conductor atoms are not included).

- College Physics -
**Kate**, Sunday, February 7, 2010 at 12:08am
Thanks for the help! And BTW, I am not switching my name.

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