The magnetic field at the centre of a circular current carrying conductor of radius r is `B_(c)` . The magnetic field on its axis at a distance r from the centre is `B_(a)`. The value of `B_(c):B_(a)` will be

Options

A. `2sqrt(2):1`
B. `sqrt(2):1`
C. `1:sqrt(2)`
D. `1:2sqrt(2)`

Answer

A

Explanation

The magnetic induction at the centre of circular wire `=(mu_(0))/(4pi)(2pii)/(r)`. Along the axis at a distance r from the centre,
`=(mu_(0))/(4pi)(2pii)/(r2sqrt(2))therefore(B_(c))/(B_("r-axial"))=2sqrt(2):1`.