A bar magnet falls from rest under gravity through the centre of a...

- A bar magnet falling through a conducting ring induces eddy currents (Lenz's law). - These currents oppose the motion, so the speed does not increase uniformly. - When the magnet is approaching the ring, induced current opposes motion (\rightarrow) speed rises slower. - As the magnet passes the center of the ring, flux change is momentarily zero (\rightarrow) no opposing force (\rightarrow) speed increases. - As the rear end leaves the ring, induced current again opposes motion (\rightarrow) temporary reduction in acceleration (or speed dips). - After leaving, only gravity acts (\rightarrow) speed increases again. Hence, the $v$ - $t$ curve shows rise (\rightarrow) dip (\rightarrow) rise, which matches graph (1).