Question

Question #c4ed5

Answer 1

We know `" "R=rhoL/A....(1)`

Where R represents the resistance of an ohmic conductor of length l and cross sectional area A and `rho` represents the resistivity of the material of the conductor.

Now we consider the situation when the V potential difference is applied across the ends of the conductor.Let I be the current flowing through it. In this situation the electric field acting with in the conductor is `E=V/L`. The current density is `i=I/A`

Multiplying both sides of (1) by I we get

`=>IR=rho(LI)/A`

By ohm's law `IR=V`

`=>V/L=rhoI/A`

`=>E=rhoi`

This equation shows that resistivity (`rho`) is the proportionality constant for current density (i) and electric field (E).