question_answer

A point charge placed at any point on the axis of an electric dipole at some large distance experiences a force F. What will be the force acting on the point charge when its distance from the dipole is doubled?                               

Answer:

                At any axial point of a dipole, electric field varies as \[E\propto \frac{1}{{{r}^{3}}}\]or \[\frac{F}{q}=\frac{1}{{{r}^{3}}}\]or \[F\propto \frac{1}{{{r}^{3}}}\] \[\therefore \] When the distance of the point charge is doubled, the force reduces to \[F/8\].