A bar magnet of mass 250 g is suspended from the free end of a spring, as illustrated in Fig. 3.1. [Figure 3.1] The magnet hangs so that one pole is near the centre of a coil of wire. The coil is connected in series with a resistor and a switch. The switch is open. The magnet is displaced vertically and then allowed to oscillate with one pole remaining inside the coil. The other pole remains outside the coil. At time t = 0, the magnet is oscillating freely as it passes through its equilibrium position. At time t = 6.0s, the switch in the circuit is closed. The variation with time t of the vertical displacement y of the magnet is shown in Fig. 3.2. [Figure 3.2]