A circular coil of 0.2 m diameter has 100 turns and carries a current of 0.1 ampere. The intensity of magnetic field at the centre of the coil is -

Explanation

Number of turns of coil, `N = 1,000`
Current in the coil , `I = 0.1A`
Radius of the ring , `R = 0.2 m`
Then, magnetic field at the centre of coil is
`B = (mu_(0)I)/(4 pi R) = (4 pi xx 10^(-7) xx 0.1)/(2 xx 0.2) = 3.14 xx 10^(-7) T`