CBSE Class 12-science Answered

Let us consider the coil 1 and coil 2 wounds over the cylindrical support. The coil 1 is connected to a battery B and a tapping key K. Coil 2 is connected to a sensitive galvanometer G as shown in the figure b.

When we press key K, galvanometer G in coil 2 shows a sudden temporary deflection. This indicates that current flowing in coil1 has induced current in coil 2. This is because the current in coil 1 increasing from zero to a certain value increases the magnetic field in coil1 and hence the number of magnetic lines of force entering coil2 on releasing key K, galvanometer G shows a sudden temporary deflection in the opposite direction because the current decreasing in the coil1 decreases the number of magnetic lines of force in coil2.

Thus, we conclude that induced emf appears in the coil whenever the amount of magnetic flux linked with the coil changes.