The GATE Grind

GATE 2026 EE – Question 15

Electromagnetic Fields · Coulomb's Law, Electric Field Intensity, Electric Flux Density, Gauss's Law, Divergence · 1 mark · Multiple choice

A uniform ring charge of radius $R$ carries a total charge $Q$. Which one of the following options correctly quantifies the magnitude of the force on a point charge of strength $q$ kept at the center of the ring?

($\epsilon$ is the permittivity of the medium)

  1. $\dfrac{Qq}{4\pi\epsilon R}$
  2. $\dfrac{Qq}{4\pi\epsilon R^2}$
  3. 0
  4. $\dfrac{q}{4\pi\epsilon R}\times\dfrac{Q}{2\pi R}$

Practise this question in The GATE Grind →

Show answer and explanation

Correct answer: (C) 0

Explanation

By symmetry, every element of the ring has a diametrically opposite element that produces an equal and opposite force on the charge at the centre. The forces cancel and the net force is 0.