The figure shows a nonconducting ring which has positive and negative charge non uniformly distributed on it such that the total charge is zero. Which of the following statements is true ?
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Options

A. The potential at all the points on the axis will be zero
B. The electric field at all the points on the axis will be zero
C. The direction of electric field at all points on the axis will be along the axis
D. If the ring is placed inside a uniform external electric field then net torque and force acting on the ring would be zero

Answer

A

Explanation

Potential at all point on axis is zero as any point on the axis is equidistant from positive & negative charge. Net electric field due to ring on the axis will be perpendicular to axis. Ring can be seen as a dipole with dipole moment perpendicular to axis. When placed in uniform external field F = 0 but t may not be zero.