The mutual inductance M12 of coil 1 with respect to coil 2
(a) increases when they are brought nearer
(b) depends on the current passing through the coils
(c) increases when one of them is rotated about an axis
(d) is the same as M21 of coil 2 with respect to coil 1
The correct answers are the options (a, d)
According to Faraday's second law emf induces in secondary
The mutual inductance M12 of coil 1 wrt coil 2 increases when they are brought nearer and is the same as M21 of coil with respect to coil 1.
M12 e.g. mutual inductance of solenoid S1 with respected to solenoid S2 is given by
Where signs are as usual,
Also, M21, i.e. mutual inductance of solenoid S2 with respect to solenoid S1 is given by:
So we have