Magnetic field at the centre of a circular coil of rradius R due to current I flowing through it is B. The magnetic field at a point along the axis at distance R from the centre is

Options

A. `B/2`
B. `B/4`
C. `(B)/(sqrt(8))`
D. `sqrt(8)B`

Answer

C

Explanation

The magnetic field at the centre of a circular coil of radius R carrying current I is
`B=(mu_(0)2piI)/(4piR)=(mu_(0I))/(2R)`
The magnetic field at a point along the axis at distance R from the centre of a circular coil of radius R carrying current I is
`B_(A)=(mu_(0)2piIR^(2))/(4pi(R^(2)+R^(2))^(3//2))=(mu_(0)I)/(2sqrt(8)R)=(B)/(sqrt(8))`