Two 120 V light bulbs, one of 25 W other of 200 W were connected in series across a 240 V line. One bulb burnt out almost instantaneously. Which one was burnt and why ?

Explanation

since the b ulbs are connected in series, th erefore same current will flow in them. The resistance of 200W bulb is less than 25W. Therefore more potential difference than 120V will be developed in 25W bulb hence it will fuse.