Which of the following is a vector quantity?

Drift speed $(v_d)$ varies with the intensity of the electric field $(E)$ as per the relation:

$A$ cylindrical conductor of diameter $0.1 \text{ mm}$ carries a current of $90 \text{ mA}$. The current density (in $\text{Am}^{-2}$) is (take $\pi \simeq 3$):

The $SI$ unit of the current density is . . . . . . .

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

Charge passing through a conductor of cross-section area $A=0.3 \,m^2$ is given by $q=3 t^2+5 t+2$ in coulomb,where $t$ is in second. What is the value of drift velocity at $t=2 \,s$ ? (Given,$n=2 \times 10^{25} / m^3$ )