Concepts Of Physics MCQ Edition [Volume 2]PhysicsElectric Field and Potential
For a uniformly charged ring of radius R , determine the distance from its centre along the axis where the electric field achieves its maximum value.
Options
- A2R
- BR 2
- CR 2
- DR 2
Correct answer
D. R 2
Step-by-step solution
The electric field at a distance x from the centre of a uniformly charged ring of radius R and charge Q on its axis is given by E = kQx (R^2 + x^2)^ 3/2 For the electric field to be maximum, dE dx = 0 d dx [ x (R^2 + x^2)^ 3/2 ] = 0 (R^2 + x^2)^ 3/2 1 - x 3 2 (R^2 + x^2)^ 1/2 2x (R^2 + x^2)^3 = 0 (R^2 + x^2)^ 1/2 [R^2 + x^2 - 3x^2] = 0 R^2 - 2x^2 = 0 x = R 2