Question

Magnetic field due to a ring having `n` turns at a distance `x` on its axis is proportional to (if, `r` = radius of ring)

Options:
(a) `r/((x^2+r^2))` (b) `r/((x^2+r^2)(3/2))`
(c) `(nr^2)/((x^2+r^2)(3/2))` (d) `(n^2r^2)/((x^2+r^2)(3/2))`