The ratio of magnetic fields on the axis of a cricular current cerrying coil of radius a to the magnetic field at its centre lying on the periphery of the surface of the sphere will be .

Options

A. `(1)/((1+(a^2)/(x^2))^(3//2))`
B. `(1)/((1+a^2/x^2)^(1//2))`
C. `(1)/((1+a^2/x^2)^(2))`
D. `(1)/((1+a^2/x^2)^(3))`

Answer

A