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Directions : (41-45)

Potentiometer: An ideal Voltmeter

Potentiometer is an apparatus used for measuring the emf of a cell or potential difference between two points in an electrical circuit accurately. It is also used to determine the internal resistance of a primary cell. The potentiometer is based on the principle that, if V is the potential difference across any portion of the wire of length / and resistance R. then \[V\propto l\] or \[V=kl\] where k is the potential gradient. Thus, potential difference across any portion of potentiometer wire is directly proportional to length of the wire of that portion. The potentiometer wire must be uniform. The resistance of potentiometer wire should be high.

Which one of the following is true about potentiometer?

A) Its sensitivity is low.

B) It measures the emf of a cell very accurately

C) It is based on deflection method

D) None of these