To find the frequency of AC mains by sonometer method. It consists of suitable electromagnet with step down transformer of fixed voltages 6 V & 8 V having current capacity 2 A. When this attachment is supported over a Sonometer and connected to a source of alternating current the wire will vibrate continuously. By adjusting the tension and the bridge position maximum resonance can be obtained. Supplied without Sonometer and without stand for holding the electromagnet
