Current through a wire help

  • Thread starter aftershock
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Homework Statement






A current of I=8.0A is flowing in a typical extension cord of length L=3.00m. The cord is made of copper wire with diameter d=1.5mm.

The charge of the electron is e=1.6*10^-19C. The resisitivity of copper is [tex]\rho[/tex]=1.7*10^-8[tex]\Omega[/tex] m. The concentration of free electrons in copper is n=8.5*10^28m^-3



Homework Equations



I honestly have no idea. There's nothing in my book about collisions at all other than saying that's what causes resistance.

The Attempt at a Solution



Honestly have no idea where to begin... there is literally not a thing about this in my book. It's from an online homework assignment.
 

Answers and Replies

  • #2
tiny-tim
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hi aftershock! :smile:

erm :redface:what's the question? :confused:
 
  • #3
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hi aftershock! :smile:

erm :redface:what's the question? :confused:

Wow I can't believe I left that part off, sorry.

Find the total number of collisions that all free electrons undergo in one second.

I was able to see the answer and the equation used was something along the lines of m/([tex]\rho[/tex]ne2)

I have no idea where that came from though.
 
  • #4
tiny-tim
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Wow I can't believe I left that part off, sorry.

he he :biggrin:
Find the total number of collisions that all free electrons undergo in one second.

I was able to see the answer and the equation used was something along the lines of m/([tex]\rho[/tex]ne2)

I have no idea where that came from though.

not something i'm familiar with :redface:, but you might get some help from http://en.wikipedia.org/wiki/Classical_and_quantum_conductivity#Classical_conductivity http://en.wikipedia.org/wiki/Drude_model or http://en.wikipedia.org/wiki/Ohm's_Law :smile:
 

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