25.4 Self Inductin and Mutual Induction
When a tme-dependent i.e. a varying current flows through a coil, the flux through the coil )due to the magnetic field produced by current in it) will keep on changing. Hence an induced e.m.f. will be produced in it. This process is called self induction.
For any given coil it is found that
, where L is constant for the given coil.
The quantity L depends on the geometry of the coil and is called Coefficient of Self Inductance.
S.I Unit of L = 1 Volt / 1 Amp / sec = 1 Henry
: 1 Volt / Amp = 1 Ohm
\ 1 Henry = 1 Ohm
If two coils are kept close to each other and if a varying current flows through one of them then the
intensity of the magnetic field intensity () due to the current will vary. Hence flux through the other coil
will keep on changing with time; therefore an e. m. f. will be induced in the other coil. For any
given combination of coils it is found that , where M is constant and is called the Coefficient of Mutual Inductance of the given arrangement of the given coils. The quantity M, like L, also depends on the geometry of coils and their arrangements.
S.I Unit of M = 1 henry.