Cross-sectional area of a copper wire is equal to the area of a square of length $2 \ mm$. If this copper wire draws $8 \ A$ electric current,then find the drift velocity of free electrons. The number density of electrons in the copper wire is $8 \times 10^{28} \ m^{-3}$.

If $n, e, \tau$ and $m$ respectively represent the electron density,charge,relaxation time,and mass of the electron,then the resistance of a wire of length $l$ and area of cross-section $A$ will be

$A$. The drift velocity of electrons decreases with the increase in the temperature of a conductor.
$B$. The drift velocity is inversely proportional to the area of cross-section of a given conductor.
$C$. The drift velocity does not depend on the applied potential difference to the conductor.
$D$. The drift velocity of an electron is inversely proportional to the length of the conductor.
$E$. The drift velocity increases with the increase in the temperature of a conductor.
Choose the correct answer from the options given below:

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

Explain the drift of electrons and drift velocity. Derive the equation for electric current in terms of the cross-sectional area of a conductor.

Why is current not formed in solid conductors in the absence of an electric field?