Find the Electric Field strength

  • Thread starter Zorba
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  • #1
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Homework Statement


"A copper cable carrying 50A current has radius 0.003m. What is the electric field if copper has a resistivity of 1.7x10^-8 Ohm/m?"

Homework Equations


Formula for current density etc.

The Attempt at a Solution



So I write:
[tex]\vec{\mathbf{J}} = n|q|v_d = \frac{I}{A}[/tex]

And then:
[tex]\vec{\mathbf{J}} \cdot \rho = \frac{I}{A} \cdot \frac{RA}{L} = \frac{V}{L}[/tex]

And now do I just apply the work energy theorem?:
[tex] \int \vec{\mathbf{E}} \cdot d\vec{\mathbf{l}} = \Delta V_{ab}[/tex]

It kind of feels as though I'm completely off tbh...
 

Answers and Replies

  • #2
Cyosis
Homework Helper
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Use Ohm's law [itex]\mathbf{J}=\sigma \mathbf{E}[/itex].
 

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