Question

The potentiometer is more appropriate for measuring potential difference than a voltmeter because difference than a voltmeter because
(A) the resistance of voltmeter is high
(B) the sensitivity of a potentiometer is higher than that of voltmeter
(C) the resistance of potentiometer wire is very low
(D) the potentiometer does not draw any current from the unknown source of emf

Answer 1

Hint
A potentiometer is a three-terminal resistor with a sliding or rotating contact that forms an adjustable voltage divider. If only two terminals are used, one end and the wiper, it acts as a variable resistor or rheostat.

Complete step by step answer
A voltmeter, when connected across two points, develops little current through itself due to the potential difference between the two points. This changes the actual circuit and hence an accurate reading is not obtained.
A potentiometer reading is based on finding an equipotential point such that no current flows. The circuit is not affected in such cases and a more appropriate reading is obtained. It does not draw current from source.
Option (D) is correct.

Note
A voltmeter is an instrument used for measuring electric potential difference between two points in an electric circuit. Analog voltmeters move a pointer across a scale in proportion to the voltage of the circuit; digital voltmeters give a numerical display of voltage by use of an analog-to-digital converter.