Question

A given charge situated at a certain distance from an electric dipole in the end on position, experiences a force F. If the distance of the charge is doubled, the force acting on the charge will be :

• A. F/8
• B. F/4
• C. F/2
• D. 2F

Answer 1

The correct option is A F/8

The electric field at a distance $r$ from the dipole is $\overrightarrow{E}=K\frac{2P}{r^3}$

, so $E\propto \frac{1}{r^3}$

Force on charge q is $F=qE$ also $F\propto \frac{1}{r^3}$

If distance $r$ is doubled, then force will $F^{\prime }=\frac{F}{8}$