In the following diagram, the work done in moving a point charge from point $P$ to points $A, B$ and $C$ is $W_A, W_B$ and $W_C$ respectively. If there is no charge nearby, then:

Two point charges of $1 \text{ nC}$ and $2 \text{ nC}$ are placed at two corners of an equilateral triangle of side $3 \text{ cm}$. The work done in bringing a charge of $3 \text{ nC}$ from infinity to the third corner of the triangle is . . . . . . $\mu\text{J}$. $( \frac{1}{4\pi\epsilon_{0}} = 9 \times 10^{9} \text{ N.m}^{2}/\text{C}^{2} )$

The electric potential at a point at a distance $x$ from the center inside a conducting sphere of radius $R$ charged with charge $Q$ is:

$A$ pellet carrying a charge of $0.5 \, C$ is accelerated through a potential difference of $2000 \, V$. The kinetic energy attained by the pellet is:

How much kinetic energy will be gained by an $\alpha$-particle in going from a point at $70\,V$ to another point at $50\,V$?

$A$ thin metallic disc is rotating with constant angular velocity about a vertical axis that is perpendicular to its plane and passes through its centre. The rotation causes the free electrons in the disc to redistribute. Assume that there is no external electric or magnetic field. Then,