The quantities that do not change when a resistor connected to a battery is heated due to the current are:
$(A)$ drift speed
$(B)$ resistivity
$(C)$ resistance
$(D)$ number of free electrons

$A$ current of $5\; A$ is passing through a non-linear magnesium wire of cross-section $0.04\; m^2$. At every point,the direction of current density is at an angle of $60^{\circ}$ with the unit vector of the area of cross-section. The magnitude of the electric field at every point of the conductor is .... $V/m$ (Resistivity of magnesium is $\rho = 44 \times 10^{-8}\, \Omega m$).

$A$ conductor of length $100 \, cm$ and area of cross-section $1 \, mm^2$ carries a current of $5 \, A$. If the resistivity of the material of the conductor is $3.0 \times 10^{-8} \, \Omega \cdot m$, then the electric field across the conductor is (in $ \, V/m$)

When a potential difference is applied across the ends of a linear metallic conductor,

Derive the relation between electric current and drift velocity.

When the current $i$ is flowing through a conductor,the drift velocity is $v$. If $2i$ current is flowed through the same metal but having double the area of cross-section,then the drift velocity will be