$A$ potential difference is applied across the ends of a metallic wire. If the potential difference is doubled,then the drift velocity

$A$ wire of diameter $0.02\,m$ contains $10^{28}$ free electrons per cubic meter. For an electrical current of $100\,A$,the drift velocity of the free electrons in the wire is nearly:

$A$ current $I$ flows through a uniform wire of diameter $d$ when the mean electron drift velocity is $V$. The same current will flow through a wire of diameter $d/2$ made of the same material if the mean drift velocity of the electron is:

What is current density? Derive Ohm's law in the form of current density.

Two identical conductors are kept at the same temperature. If the ratio of the potential difference across them is $1 : 2$,what will be the ratio of their drift velocities?

An electric current passes through a wire of non-uniform cross-section,made of a homogeneous and isotropic material. If $j_A$ and $j_B$ are the current densities and $E_A$ and $E_B$ are the electric field intensities at $A$ and $B$ respectively,then $-$