When we have a source of emf then generating a current is easy but, suppose we need a current but we don’t have any source.
We still can by using the principle of electromagnetic induction.
We need a coil , a galvanometer and a bar magnet for this.
The galvanometer should be connected to the coil to detect the current in it.
Let’s generate a current without source
Take the bar magnet near the coil-galvanometer arrangement.
And move the bar magnet towards the coil.
Surprised! Yes the galvanometer is deflected. A current is there even without a battery.
Let’s understand why is there a current without battery and what is it called!
This current without the battery is the induced current.
When the bar magnet moves toward the coil ,then the galvanometer shows some deflection.
Because the field lines of the magnet cuts the coil and a current is induced in the circuit.
Now let’s see what happens when the bar magnet moves away from the coil
If magnet moves away from the coil ,deflection in galvanometer is in the opposite direction.
So, the field lines associated is moving away from the coil and thus coil cuts them and current is induced.
Now, let’s check what will happen when the magnet is not moving
When the bar magnet and the coil are kept at some distance and there is no motion in bar magnet
Then, we observe that there is no deflection in galvanometer that means no current is induced in the circuit
Because the field line is not cutting in the coil so, no current will induced
This experiment was done by Michael Faraday. So this experiment is known as “Faraday’s Experiment”.
In this experiment he also found that the velocity of bar magnet is proportional to induced current
When a magnet is brought towards a coil,current is induced in the circuit, and galvanometer deflects.
When bar magnet moves in opposite direction then the galvanometer deflects opposite to initial deflection.
When there is no movement in the bar magnet , there is no deflection.
The velocity of bar magnet is proportional to current.
This principle is used vastly in generation of electricity in commercial scale.
We will see more but that’s it for now.