Question

Collect information of experiments done by Faraday.

Answer 1

Experiment – 1

1. Connect the terminals of a coil to a sensitive galvanometer as shown in the figure.

2. Normally, we would not expect any deflection of needle in the galvanometer because there is no EMF in the circuit. 

3. Now, if we push a bar magnet towards the coil, with its north pole facing the coil, the needle in the galvanometer deflects, showing that a current has been set up in the coil, the galvanometer does not deflect if the magnet is at rest. 

4. If the magnet is moved away from the coil, the needle in the galvanometer again deflects, but in the opposite direction, which means that a current is set up in the coil in the opposite direction. 

5. If we use the end of south pole of a magnet instead of north pole, the results i.e., the deflections in galvanometer are exactly opposite to the previous one. 

6. This activity proves that the change in magnetic flux linked with a closed coil, produces current. 

7. From this Faraday’s law of induction can be stated as “whenever there is a continuous change of magnetic flux linked with a closed coil, a current is generated in the coil”. This induced EMF is equal to the rate of change of magnetic flux passing through it.

Experiment – 2

1. Prepare a coil of copper wire C₁ and connect the two ends of the coil to a galvanometer. 

2. Prepare another coil of copper wire similar to C₂ and connect the two ends of the coil to a battery via switch. 

3. Now arrange the two coils C₁ and C₂ nearby as shown in the figure. 

4. Now switch on the coil C₂. We observe a deflection in the galvanometer connected to the coil C₁. 

5. The steady current in C₂ produces steady magnetic field. As coil C₂ is moved towards the coil C₁ the galvanometer shows a deflection.

6. This indicates that electric current is induced in coil C₁. 

7. When C₂ is moved away, the galvanometer shows a deflection again, but this time in the opposite direction.

8. The deflection lasts as long as coil C₂ is in motion. 

9. When C₂ is fixed and C₁ is moved, the same effects are observed. 

10. This shows the induced EMF due to relative motion between two coils.