A thin ring of radius R meter has charge q coulomb uniformly spread on it. The ring rotates about its axis with a constant frequency of f revolutions/s. The value of magnetic induction in `Wb//m^2` at the centre of the ring

Options

A. `(mu_0 qf)/(2pi R)`
B. `(mu_0q)/(2pi fR)`
C. `(mu_0q)/(2 fR)`
D. `(mu_0qf)/(2R)`

Answer

D

Explanation

Current produced due to circular motion of charge q is I= q f
Magnetic field induction at the centre of the ring of radius R is
`B= (mu_0 2pi l)/(4 pi R) = (mu_0 l)/(2 R ) = (mu_0ef)/(2R)` (Using (i))