Question

Why potentiometer is preferred over voltmeter?

Answer 1

Voltmeter:

A voltmeter is an instrument that is used to measure the potential difference between two points in an electrical circuit.

Potentiometer:

The potentiometer is an instrument that is used to measure the EMF of a cell and also works as a voltage divider.

Comparison of potentiometer over voltmeter.

1. Voltmeter and Potentiometer both measure voltage. but potentiometer measures exact value whereas voltmeter measures approx value.
2. The potentiometer does not draw any current while measuring emf whereas the voltmeter draws current to measure emf.
3. A potentiometer work on the no deflection method whereas, a voltmeter works on the deflection method.
4. A potentiometer has high sensitivity but a voltmeter has low sensitivity.
5. Potentiometer is also used to measure the internal resistance of a cell whereas a voltmeter can not be used to measure the internal resistance of a cell.

So that is why the Potentiometer is preferred over the voltmeter.