Explain the phenomenon of electromagnetic induction. Describe an experiment to show that a current is set up in a closed loop when an external magnetic field passing through the loop increases or decreases.
Electromagnetic Induction: This was first demonstrated by Michael faraday in 1831. When a conductor and magnetic field are in motion relative to each other, electric currents is induced in the conductor. This phenomenon is called electromagnetic induction.
• Take two coils with large number of turns. Let us assume that number of turns in one coil
is 100 and in another coil it is 50.
• Insert a cylinder of a non-conducting material through these coils.
• Connect the coil with 50 turns to a galvanometer.
• Connect the coil with 100 turns to a battery and plug key.
Observation:
• When key is switched on, deflection is seen in galvanometer.
• When key is switched off, deflection is seen in galvanometer; but in opposite direction.
• This shows that whenever there is a change in strength of magnetic field, current is induced in the coil.
