When a Wheatstone bridge is perfectly balanced, what will the meter read?

A Wheatstone bridge is an electrical circuit used to measure an unknown resistance by balancing two legs of a bridge circuit. When the bridge is perfectly balanced, the electrical potential difference (voltage) between the two points in the bridge (where the meter is connected) becomes equal. This means that there is no net voltage present across the meter leads, leading to a reading of zero.

In this balanced state, the currents through both branches of the circuit are equal, and thus no current flows through the meter. As a result, the meter, which is typically a galvanometer, will show a reading of zero. This principle is vital in precise resistance measurement, as it indicates that the ratio of the two known resistances equals the ratio of the unknown resistance and another known resistance.

Understanding that the key concept here is the balance of voltages across the bridge leads to a clear comprehension of the functionality of a Wheatstone bridge. When the meter reads zero, it signifies that equilibrium is achieved and the measurement conditions are ideal for determining resistance.