Answer the following:
(a) Derive the expression for the electric potential at any point P, at distance r from the centre of an electric dipole, making angle `alpha`, with its axis.
(b) Two point charges `4 mu C and + 1 mu C` are separated by a distance of 2m in air. Find the point on the line joining charges at which the net electric field of the system is zero.

Explanation

### Solution:

#### Part (a): Deriving the Expression for Electric Potential at Point P

1. **Understanding the Electric Dipole**:
An electric dipole consists of two equal and opposite charges, +Q and -Q, separated by a distance of 2a. The dipole moment \( \vec{p} \) is defined as \( \vec{p} = Q \cdot 2a \).

2. **Positioning the Point P**:
...