Write principle of potentiometer. Why potentiometer is preferred over voltmeter for measurement of emf of cell. For the potentiometer circuit shown in figure, point X andY represent the two terminals of an emf E.
. , A student observed that when the jockey is moved from the end A to the end B of the potentiometer wire, the deflection in the galvanometer remain in the same direction.
What may be the two possible faults in the circuit that could result in this observation? If the galvanometer
deflection at the end B is (i) more, (ii) less , than that at the end A, which of the two faults, listed above, would be there ln the circuit? Give reasons in support of your answer in each case.
Potentiometer is an apparatus used for measuring the emf of a cell or potential difference between two points in an electric circuit accurately. When there is no potential difference between two points there no electric current will flow, this is the basic potentiometer principle.
Potentiometer is preferred over voltmeter for measurement of emf of cell it is because potentiometer doesn't draw any current for itself from the primary circuit and hence gives more accurate measurement thereby acting as an ideal voltmeter. It uses null method to measure.
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