$A$ proton is accelerated through $50,000 \, V$. Its energy will increase by

If four charges $+12 \text{ nC}, -20 \text{ nC}, +32 \text{ nC}$ and $-15 \text{ nC}$ are arranged at the four vertices of a square of side $\sqrt{2} \text{ m}$,then the net electric potential at the centre of the square due to these four charges is (in $\text{ V}$)

Consider a sphere of radius $R$ with uniform charge density and total charge $Q$. The electrostatic potential distribution inside the sphere is given by $V(r) = \frac{Q}{4 \pi \varepsilon_{0} R} \left( a + b(r/R)^c \right)$. Note that the zero of potential is at infinity. The values of $(a, b, c)$ are

The electric potential at the surface of a hollow metallic sphere is $10\, V$. What will be the electric potential at its center (in $, V$)?

Two concentric hollow spheres of radii $r$ and $R$ $(R > r)$ have the same surface charge density $\sigma$. The total charge $Q$ is distributed between them. The electric potential at the common center is:

Assertion: Electrons move away from a region of higher potential to a region of lower potential.
Reason: An electron has a negative charge.