Construction and Working of Metre Bridge | Physics Video Tutorials
Metre bridge is one form of Wheatstone’s bridge. Metre bridge consists of thick strips of copper, of negligible resistance, fixed to a wooden board. There are two gaps G1 and G2 between these strips. A uniform manganin wire AC of length one metre whose temperature coefficient is low, is stretched along a metre scale and its ends are soldered to two copper strips. An unknown resistance P is connected in the gap G1 and a standard resistance Q is connected in the gap G2. A metal jockey J is connected to B through a
galvanometer (G) and a high resistance (HR) and it can make contact at any point on the wire AC. Across the two ends of the wire, a Leclanche cell and a key are connected.
Adjust the position of metal jockey on metre bridge wire so that the galvanometer shows zero deflection. Let the point be J. The portions AJ and JC of the wire now replace the resistances R and S of Wheatstone’s bridge.
