What are the applications of self and mutually induced emf?

							
Self induced EMF opposes the applied voltage due to the changing current (AC). The common name for this device is an “inductor”. They are used in an innumerable number of circuits in power and electronics for many different purposes.
The very common use of this device is to limit the current through a discharge lamp like fluorescent tubes. Mercury and sodium vapour lamps when the lamp is on. This device is called a ballast or choke. It (chokes the current). The ballast or choke performs another function too. When the starter interrupts the current through the tube the rapidly collapsing magnetic field produces a very high voltage that ignites the tube.
						

							
Dear student 
If the current flowing through the coil A is changed by changing the value of variable resistor R, it changes flux linking with the other coil B and hence emf is induced in the coil. This induced emf is called Mutually Induced emf.
Self-induced emf is the e.m.f induced in the coil due to the change of flux produced by linking it with its own turns.