If in a circular coil A of radius R, current I is flowing and in another coil B of radius 2R a current 2I is flowing, then the ratio of the magnetic fields BA and BB, produced by them will be
Magnetic field at the centre of the coil is given by
B = (μoNI)/(2R)
Since both current (numerator) and radius (denominator) are doubled, the magnetic field produced by coil A and B will be same. So, the ratio will be 1.
The correct option is C.