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If a current passes through a metal cond...

If a current passes through a metal conducting wire of area of cross section A, the drift velocity of free electrons inside the metal is `v_d=1/( n e A)` , where the amount of electric charge of an electron =e and the number of free electrons per unit volume of the metal=n. The applied electric field on the wire is `E=V/l`, where a potential difference V exists between two points, l apart, along the length of the wire. IF R is the resistance of the wire between those two points, then the resistivity of its material is `rho=(RA)/l`.Besides the mobility `(mu)` of the free electrons inside a wire is defined as their drift velocity for a unit applied electric field.
The current through unit cross section of a conductor,called the electric current density J, is related with the applied electric field E as

A

`J=rhoE`

B

`J=1/rhoE`

C

`J=muE`

D

`J=1/muE`

Text Solution

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The correct Answer is:
B
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