The magnitude of the drift velocity per unit electric field is known as . . . . . . .

$A$ battery is connected to a uniform resistance wire $AB$ and $B$ is earthed. Which one of the graphs below shows how the current density $J$ varies along $AB$?

$A$ wire of cross-sectional radius $r$ carries a current $I$ due to free electrons moving with a drift velocity $V$. What will be the current in another wire of the same material having half the radius and a drift velocity of $2V$?

When $5\ V$ potential difference is applied across a wire of length $0.1\ m$,the drift speed of electrons is $2.5 \times 10^{-4} \ m/s$. If the electron density in the wire is $8 \times 10^{28} \ m^{-3}$,the resistivity of the material is close to:

For a cylinder of radius $R$,the current density is given by $J = J_0 \frac{r}{R}$,where $J_0$ is a constant and $r$ is the distance from the axis. Calculate the total current.

What is relaxation time?