Question

Potentiometer measures potential more accurately because
A) It measures potential in an open circuit.
B) It uses a sensitive galvanometer for null deflection.
C) It uses high resistance potentiometer wire.
D) It measures potential in a closed circuit.

Answer 1

Hint: The potentiometer doesn’t require flow of current passing through its galvanometer for the measurement of measurement. We know that the open circuit is in which the current in the two terminals of the component is zero and in closed circuit, the current flows through the two terminals.

Complete step by step answer:
We know that the potentiometer is used to measure the potential difference between the two points in a circuit. The resistance of the potentiometer is very high. To measure the voltage across any circuit component, the potentiometer is connected across it, in parallel to the circuit component.

We know from Ohm’s law, the current flowing through a circuit component is inversely proportional to the resistance of the component. Therefore, the current flowing through the galvanometer of potentiometer is almost zero as the potentiometer has large resistance. Therefore, the circuit is in an open circuit state as no current flows through the ends of the potentiometer. So, the option (A) will be the correct answer.

We need to verify other options as well.

(B) Galvanometer is used in potentiometers to measure the amount of current flow if any. Since the current through the potentiometer is almost zero as the resistance is very large, the use of a galvanometer in the potentiometer is to show the null deflection.

(C) Potentiometer does not use any high resistance wire to increase the resistance.

(D) Potentiometer is connected in open circuit and not in closed circuit.

Hence, option (A) is the only correct option.

Note: Galvanometer uses high resistance to restrict the flow of current through it. We can also use an ideal voltmeter as it has infinite resistance to measure the potential difference across the two points in the circuit. But practically, no voltmeter is an ideal voltmeter.