Question

When is the Wheatstone bridge said to be most sensitive?

Answer 1

Hint: In order to answer this question, it is essential to know about the working of Wheatstone’s bridge. Wheatstone bridge is an electrical bridge constructed using two legs to find out the value of unknown components. It consists of 4 resistors in two series parallel arrangements.

Complete Step By Step Solution
The Wheatstone bridge is a simple electrical circuit developed by Charles Wheatstone to measure the unknown resistance value offered by the circuit or load by means of measuring instruments. This has been deemed as the simplest way to measure resistance in the circuit. It is mainly used in many electronics applications such as in load cells and amplifiers.
The construction of the bridge consists of 2 series connected resistors that are connected parallel to each other , where one series leg is connected to the voltage terminal and other to the ground, producing no voltage difference between the parallel branches, thus said to be in balanced state.
In electrical terms, bridge sensitivity is defined as the amount of deflection of the attached galvanometer per unit change in unknown resistance present in the circuit. So naturally, the wheatstone bridge will have a sensitivity of certain value. A Wheatstone bridge is said to have maximum sensitivity when it is in balanced state and the magnitude of resistors attached in the bridge are of the same magnitude. In layman terms, all four resistors provide the same output resistance.

Note: Wheatstone bridge configuration is applied to measure small variations in resistance which are produced by sensors , which respond to a change in physical stimuli. One such example is usage of a bridge in a load cell sensor to calculate the mass of the unknown object using change in resistance due to physical change in the sensor.