A current carrying coil has self inductance that is a property by which it may store energy. The inductance among two coils is called mutual inductance. We will elaborate on these with examples. While two coils are coupled together, flux in one coil is linked with the other. The coefficient of coupling between two coils gives idea regarding the degree of this linking. We shall study about it.
While two coils are mutually coupled, their emfs can be aiding or opposing and it is determined by dot convention which shall be illustrated. Two current carrying coils may be connected in series or parallel. Series and parallel connection may again be aiding or opposing.