
N equally spaced charges each of value q, are placed on a circle of radius R. The circle rotates about its axis with an angular velocity as shown in the figure. A bigger Amperian loop B encloses the whole circle where as a smaller Amperian loop A encloses a small segment. The difference between enclosed currents, , for the given Amperian loops is [2025]
(3)
Now for bigger Amperian loop (loop B)

And for smaller Amperian loop (loop A)
So,