A) it has a wire of high resistance
B) it has a wire of low resistance
C) it does not draw current from external circuit
D) it draws a heavy current from external circuit
Correct Answer: C
Solution :
When we measure the emf of a cell by the potentiometer then no current draws in the circuit in zero-deflection condition i.e., cell is in open circuit. Thus, in this condition the actual value of a cell is found. In this way potentiometer is equivalent to an ideal voltmeter of infinite resistance. Note: The emf by the potentiometer is measured from null method in which zero deflection position is found on the wire.
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