Define mutual inductance and mention 2 factors on which it depends
Answers
Definition: Mutual Inductance between the two coils is defined as the property of the coil due to which it opposes the change of current in the other coil, or you can say in the neighboring coil. When the current in the neighboring coil is changing, the flux sets up in the coil and because of this changing flux emf is induced in the coil called Mutually Induced emf and the phenomenon is known as Mutual Inductance.
If the mutual flux is in a medium such as air then the magnetic flux density and will be ~ \mu_0.
If the medium is iron then the magnetic flux density will be some 10000 times stronger (~\mu_0*10000).
Similarly the inductance will likewise be dependent on the medium / material.
That is why all electrical machines utilise ferro-magnetic materials so as to exploit their very high internal flux density.