Question

The distance between the two charges +q and -q of a dipole is r. On the axial line at a distance d from the centre of dipole, the intensity is proportional to

• A. $\frac{q}{d^2}$
• B. $\frac{qr}{d^2}$
• C. $\frac{q}{d^3}$
• D. $\frac{qr}{d^3}$

Answer 1

The correct option is D $\frac{qr}{d^3}$

Field along the axis of the dipole
$E=\frac{1}{4\pi {ϵ}_0}.\frac{2p}{d^3}=\frac{1}{4\pi {ϵ}_0}.\frac{2(q\times r)}{d^3};\therefore E\propto \frac{qr}{d^3}$