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

In the given hollow cylindrical conductor,the current density is $J = \frac{J_0}{r^2}$,where $J_0$ is a constant and $r$ is the distance from the axis of the cylinder. If the radius of the inner surface is $a$ and the radius of the outer surface is $2a$,find the current passed through the conductor.

Is the motion of a charge across a junction momentum conserving? Why or why not?

An ionization chamber with parallel conducting plates as anode and cathode has $5 \times 10^7$ electrons and the same number of singly-charged positive ions per $cm^3$. The electrons are moving at $0.4\, m/s$. The current density from anode to cathode is $4\,\mu A/m^2$. The velocity of positive ions moving towards cathode is ............. $m/s$. [$AIPMT$ $1992$]

$A$ conductor wire having $10^{29}$ free electrons $/ m^{3}$ carries a current of $20 \,A$. If the cross-section of the wire is $1 \,mm^{2}$, then the drift velocity of electrons will be. $\left(e=1.6 \times 10^{-19} \,C\right)$

In a conductor,if the number of conduction electrons per unit volume is $8.5 \times 10^{28} \ m^{-3}$ and the mean free time is $25 \ fs$ (femtosecond),what is its approximate resistivity? (Given: $m_e = 9.1 \times 10^{-31} \ kg$,$e = 1.6 \times 10^{-19} \ C$)