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Current through a wire help

  • Thread starter XodoX
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1. A copper wire has a diameter of 1 [mm]. The density of the copper atoms inside the wire is 8.47 × 1028 [atoms/m3]. What is the charge that is free to move in a one-meter length of wire?

2. Assume that a current of 1 [A] is flowing from left to right through the wire in the above
problem. How fast are the electrons moving from right to left, in meters per second? (Hint:
consider how much charge has moved past a given point, from right to left, in one second.



Hello, I got these 2 problems left unresolved. I can't figure out how to do them. Don't find an equation that might satisfy these 2 problems. Any help is appreciated!
 

Answers and Replies

  • #2
LowlyPion
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1. A copper wire has a diameter of 1 [mm]. The density of the copper atoms inside the wire is 8.47 × 1028 [atoms/m3]. What is the charge that is free to move in a one-meter length of wire?

2. Assume that a current of 1 [A] is flowing from left to right through the wire in the above
problem. How fast are the electrons moving from right to left, in meters per second? (Hint:
consider how much charge has moved past a given point, from right to left, in one second.


Hello, I got these 2 problems left unresolved. I can't figure out how to do them. Don't find an equation that might satisfy these 2 problems. Any help is appreciated!
In 1) they tell you how to find the number of copper atoms. Then if you know how many free electrons there are you might be in business.

In 2) then if you know the number of carriers (copper atoms) then maybe this will help?
http://en.wikipedia.org/wiki/Drift_velocity#Derivation
 

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