Question
Thu February 07, 2013 By: Vishal Mishra

define whaetstone bridge, meter brdge.

Expert Reply
Fri February 08, 2013

Working principle of Wheatstone bridge:

It is a bridge in which four resistances are arranged with a cell and a galvanometer.

 

In the balanced situation of bridge,P/Q=R/S.The potential difference between the points A and B is zero and no current flows through the galvanometer.

Meter bridge:

Meter bridge

It is based on the principle of wheatstone bridge.

i.e. when bridge is balanced,

Where, R1, R3 = known resistances,R= Variable resistance and R4 = unknown resistance

In this bridge one lateral pair of resistances is replaced by a straight wire of length 1m of uniform cross section. And other 

pair consist of one known and one unknown resistance. One side of a galvanometer is connected between known and 

unknown resistance and other side is moved along the wire to find the null point i.e. at which galvanometer doesn't show any deflection. This point balances the bridge.

Meter bridge is a wheatstone bridge in which one lateral pair of resistances is replaced by a straight wire of length 1m of uniform cross section. And other pair consist of one known and one unknown resistance. One side of a galvanometer is connected between known ad unknown resistance and other side is moved along the wire to find the null point i.e. at which galvanometer doesn't show any deflection. This point balances the bridge.

Ask the Expert