A charge q coulomb moves in a circle at n revolution per second and the radius of the circle is r metre. Then magnetic feild at the centre of the circle is

Options

A. `(2piq)/(nr)xx10^(-7)`
B. `(2piq)/(r)xx10^(-7)`
C. `(2pinq)/(r)xx10^(-7)`
D. `(2pirn)/(q)xx10^(-7)`

Answer

C

Explanation

`i=q/T=1/(2pi//omega)=(q omega)/(2pi)=(q. 2pi n)/(2pi)=qn`
`B=(mu_(0)i)/(2r)=(mu_(0)qn)/(2r)`
`=(4pixx10^(-7)qn)/(2r)`
`=(2piqn)/rxx10^(-7)`