Question

A circular coil of ‘N’ turns and diameter ‘d’ carries a current ‘I’. It is

unwound and rewound to make another coil of diameter ‘2d’, current ‘I’

remaining the same. Calculate the ratio of the magnetic moments of the new

coil and the original coil.​

Answer 1

Answer:

Explanation:

Since the total length of the wire used remains the same,

N×πd=N′×π(2d)

⟹N′=2N​

Hence the ratio of the magnetic moments=MM′​

=INAIN′A′​=

=NAN′A′​=Nd2N′d′2​

=2