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` revolution/s. The value of magnetic induction in `Wb m^(-2)` at the centre of the ring is

Options

A. `(mu_(0) qf)/(2R)`
B. `(mu_(0)qf)/(2 pi R)`
C. `(mu_(0)q)/(2 pi f R)`
D. `(mu_(0)q)/(2 f R)`

Answer

A

Explanation

Current generated due to rotation of charge is given by
`I = q/T = qf` ( where f is the frequency of rotation . )
Magnetic field at the centre of current carrying ring is given by
`B = (mu_(0)I)/(2R) = (mu_(0) qf)/(2R)`