Self induction

Self induction The process of generation of a back emf in a conductor or in a coil is called self induction. Let’s do an activity to explain this phenomenon. Take a long insulated wire from the secondary winding of a 6V, 0.5A transformer. Then connect a six volt bulb to an AC source by using this insulated wire. We can see that the bulb glows when electricity passes through it. Convert this long wire to a solenoid and observe the change in intensity of the light. We can see that the intensity is decreasing. Why does it happen? When an AC passes through a solenoid, the magnetic flux linked with it changes. This flux change induces an emf in the solenoid. This emf opposes the emf in the circuit. Due to this the voltage in the circuit also decreases. So the intensity of the bulb also decreases. This phenomenon is self induction. Self induction is that phenomenon in which a change in electric current in a coil produces an induced emf in the coil itself. The emf due to self induction is opposite in direction of the current in the circuit, so this emf is called back emf.