Electric potential due to dielectric dipole on equatorial line at distance \( r \) from the centre of the dipole is (\( P \) = dipole moment) (assume dipole as very short).
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → \( V = 0 \)
Every point on the equatorial line is at the same distance from the two charges \( +q \) and \( -q \) of the dipole. With charges at distance \( l \) on either side of the centre, that distance is \( \sqrt{r^{2} + l^{2}} \).
\( \displaystyle V = \frac{1}{4\pi\varepsilon_0}\,\frac{q}{\sqrt{r^{2} + l^{2}}} - \frac{1}{4\pi\varepsilon_0}\,\frac{q}{\sqrt{r^{2} + l^{2}}} = 0 \)
The potentials of the two charges cancel, so \( V = 0 \) everywhere on the equatorial line.
Note: This question is from NCERT (2026-27). NTA sets numerical questions from NCERT too, so do not ignore NCERT while practising numericals.
NCERT (2026-27):
Potential Due to an Electric Dipole – “… The potential in the equatorial plane (θ = π/2) is zero.”