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_c` will be

Options

A. `sqrt2:1`
B. A circular coil carrying a certain current produces magnetic field Bo at its centre. The coil is now rewound so as to have 3 turns and the same current is passed through it. The new magnetic field at the centre is
C. `1:2sqrt2`
D. `1:sqrt2`

Answer

B