Question

A meter-bridge is based on the principle of

• A. Wheatstone bridge
• B. Variation of resistance with temperature
• C. Galvanometer
• D. None of these

Answer 1

The correct option is A Wheatstone bridge

In a meter bridge the jockey is adjusted along the scale so that the balance of the resistances is obtained for some suitable value of resistance$R$ in the resistance box. The resistance values for the wire sections of the scale can be found out from the formula $R=\rho \frac{l}{A}$ after the lengths of the respective section is read from the scale.

At balanced point the value of unknown resistance$S$ is found out by the equation $\frac{P}{Q}=\frac{R}{S}$. This same principal of ratios of resistances to find the unknown resistance is used in the wheatstone bridge.