Thank you for reporting, we will resolve it shortly
Q.
A charge situated at a certain distance along the axis of an electric dipole experience a force $F$. If the distance of the charge from the dipole is doubled, the force acting on it will become
The electric field at a point distance r from electric dipole is
E = $ \frac{ 1}{ 4 \pi \varepsilon_0} . \frac{ 2p}{ r^3 }$ $$ ..( axial line)
where pis dipole moment and ris the distance of charge from centre of dipole.
or $ E \propto \frac{ 1}{ r^3 } $
Force on charge is
F = QE
or $ F \propto \frac{ 1}{ r^3 } $
$\therefore \frac{ F_2 }{ F} = \bigg( \frac{ r }{ 2r } \bigg)^3 = \frac{ 1}{ 8 } $
or $ F_2 = \frac{ F}{ 8}$