What indicates a balanced condition in a Wheatstone Bridge?

In a Wheatstone Bridge, a balanced condition is achieved when the voltage across points A and B is zero. This occurs when the ratio of the resistances in one leg of the bridge is equal to the ratio of the resistances in the other leg. When balanced, the bridge does not allow any current to flow through the galvanometer connected between points A and B, resulting in no potential difference between these two points.

This condition confirms that the circuit is in equilibrium, meaning that the voltage drop across one pair of resistors equals the voltage drop across the other pair. It is a key principle in using the Wheatstone Bridge for measuring unknown resistances, as a balanced condition simplifies the calculations involved in determining those resistances. In contrast, other conditions like having a positive or negative voltage imply that the bridge is unbalanced and current will flow, which defeats the purpose of achieving equilibrium in the circuit.