The mechanism of the heat produced in a conductor when an electric current flows through it can be explained on the basis of

$A$ conductor of length $1.5 \ m$ and area of cross-section $3 \times 10^{-5} \ m^2$ has an electrical resistance of $15 \ \Omega$. The current density in the conductor for an electric field of $21 \ Vm^{-1}$ is

For which of the following dependencies of drift velocity $v_d$ on electric field $E$ is Ohm's law obeyed?

Mobility of free electrons in a conductor is

The drift velocity of an electron is $v_d$ in a conductor of area of cross-section $A$ and carries a current $I$. Now,the area of cross-section and current flowing through the conductor are doubled,then the new drift velocity of the electron is . . . . . . .

Explain the mobility of a charge carrier in a conductor and derive its equation.