FARADAY’S LAW OF INDUCTION
Faraday’s law of induction is one of the basic equations of electromagnetism. Figure 1.12 shows a coil connected to a galvanometer. If a bar magnet is pushed toward the coil, the galvanometer deflects. This indicates that a current has been induced in the coil. If the mag- net is held stationary with respect to the coil, the galvanometer does not deflect. If the magnet is moved away from the coil, the galvanometer deflects in the opposite direction. This indi- cates that the current induced in the coil is in the opposite direction.
Figure 1.13 shows another experiment in which when the switch S is closed, thus estab- lishing a steady current in the right-hand coil, the galvanometer deflects momentarily. When the switch is opened, the galvanometer deflects again momentarily, but in the oppo- site direction. This experiment proves that a voltage known as an electromagnetic force (emf ) is induced in the left coil when the current in the right coil changes.
