Question

For measurement of potential difference, potentiometer is preferred in comparison to voltmeter because

• A. potentiometer is more sensitive than voltmeter
• B. the resistance of potentiometer is less than voltmeter
• C. potentiometer is cheaper than voltmeter
• D. potentiometer does not take current from the circuit

Answer 1

The correct option is D potentiometer does not take current from the circuit

When measuring voltage across a resistor, the voltmeter does not have infinite resistance, and hence allows passage of finite current through it. Thus the voltage to be measured across the resistor changes a little bit.

However measuring the same using potentiometer requires passage of no current through the galvanometer. Thus no change in voltage required to measure occurs, and hence this is more accurate and preferred in comparison to voltmeter.