Elecrical Vibrator

A thin steel rod (called vibrator) is clamped at one end and passes through a small solenoid. The rod is slightly flattened at the free end and a hole is drilled in it so that a string can be tied through it. The solenoid is connected to A.C mains through a suitable lamp resistance. A permanent horse shoe magnet is mounted on the base board and a steel rod passes between them. The thin rod is magnetized longitudinally. The solenoid and a horse shoe magnet cause it to vibrate with the frequency of A.C Supply.

The length of the vibrator is adjusted until its natural frequency corresponds with that of the supply.