Verified answer

Given :

Four resistors are connected as shown in figure across a battery of 30V.

• P = 1360 Ω
• R = 300 Ω
• S = 4400 Ω

To Find :

Value of variable resistor Q and voltage across XY when bridge is balanced.

Solution :

❒ The wheatstone bridge is most sensitive when the resistance in the four arms are of the same order.

• Wheatstone bridge method is not suitable for the measurement of very low and very high resistances.

In the balanced Wheatstone bridge, the resistance in arm BD is ineffective.

For a balanced Wheatstone bridge,

By substituting the given values,

No current flow in branch BD when Wheatstone bridge is in balanced condition.

Hence in balanced condition voltage across XY will be zero.