Question: When using a potentiometer to measure an unknown voltage, what is the condition for balance?

Options:

1. The current through the potentiometer must be maximum
2. The potential difference across the galvanometer must be zero
3. The resistance of the potentiometer must be zero
4. The length of the wire must be equal to the unknown voltage

Correct Answer: The potential difference across the galvanometer must be zero

Solution:

The condition for balance in a potentiometer is that the potential difference across the galvanometer must be zero, indicating that the unknown voltage is equal to the voltage across the potentiometer wire.