Experiment . The above two experiments involved relative motion between a magnet and a coil and between two coils, respectively. Through another experiment, Faraday showed that this relative motion is not an absolute requirement. Figure .
shows two coils C and C held stationary. Coil C is connected to galvanometer G while the second coil C is connected to a battery through a tapping key K. FIGURE . Current is induced in coil C due to motion of the current carrying coil C .
FIGURE . Experimental set-up for Experiment . . It is observed that the galvanometer shows a momentary deflection when the tapping key K is pressed.
The pointer in the galvanometer returns to zero immediately. If the key is held pressed continuously, there is no deflection in the galvanometer. When the key is released, a momentory deflection is observed again, but in the opposite direction. It is also observed that the deflection increases dramatically when an iron rod is inserted into the coils along their axis.