Question

A system consists of a thin charged wire ring of radius R and a very long uniformly charged thread oriented along the axis of the ring, with one of its ends coinciding with the centre of the ring. The total charge of the ring is equal to q. The charge of the thread (per unit length) is equal to λ. Find the interaction force between the ring and the thread.

Answer 1

From the solution of 3.9, the electric field strength due to ring at a point on its axis (say x-axis) at distance x from the centre of the ring is given by:

And from symmetry vector E at every point on the axis is directed along the x-axis (Fig).

Let us consider an element (dx) on thread which carries the charge (λ dx). The electric force experienced by the element in the field of ring.

Comments

Wow, that was simple and great explaination !!
Thanks