Identify the set in which all the three materials are good conductors of electricity.

In a region,$10^{19}$ $\alpha$-particles and $10^{19}$ protons per second move to the left,while $10^{19}$ electrons move to the right per second. The current is

An electron moves with a constant speed of $4 \times 10^6 \, m/s$ in a circle of radius $10 \, cm$. Find the electric current at any point on the circle.

Number of electrons flowing per second in a conductor carrying a current of $9 \,A$ is

Explain the current formed in solid conductors in the presence of an external electric field.

The electric current in a wire varies with time as $i = (2 + 3t) \text{ A}$. Calculate the charge that passes through the cross-section of the wire in $10 \text{ s}$.