Define electric resistance of a conductor?
(b) List two factors on which resistance of a conductor depends.
(c ) Resistance of a metal wire of length 1m is `104 Omega` at `20^@C`. IF the diameter of the wire is 0.15mm, find the resistivity of the metal at that temperature.

Explanation

(c )Here length of wire L=1m, resistance R=`104 Omega` and diameter of wire D=0.15mm =`0.15 times 10^-3 m`
As per relation `R=(rho L)/A=(4 rho L)/(pi D^2)`, we have
Resistivity `rho = (pi D^2 R)/(4 L)=(22 times (0.15 times 10^-3)^2 times 104)/(7 times 4 times 1)=1.84 times 10^-6 Omega. m`