The electric field strength of a point charge decreases as the square of the distance from the charge increases. This is known as the inverse square law.

$$E=k\frac{q_1q_2}{r^2}$$

Where :

- \(E\) is the electric field strength.

- \(k\) is a constant .

- \(q_1\) and \(q_2\) are the magnitude of the charges producing the electric field.

- \(r\) is the distance between the charges.