Question

State the advantages of a potentiometer over the voltmeter.

Answer 1

Hint: The potentiometer is an instrument used for measuring the EMF by balancing the EMF against the potential difference that is produced by passing through the known amount of current. The voltmeter is a device that measures the voltage across its terminal using a larger resistance value so that the current drawn is very minimum.

Step by step solution:
There are many advantages of potentiometer over the voltmeter and the importance of them can be described as below:

One of the main differences is that potentiometers work on the principle of zero deflection method and hence the possibility of error is very small in this case whereas voltmeter draws some amount of current using a high resistance value and measures the voltage. So the voltage measured by the voltmeter might have some errors.

Also, the standardization of potentiometers can be done directly with standard cells.
The potentiometer is a highly sensitive device and hence we can measure even a small EMF but in case of a voltmeter, we cannot measure a small EMF.

There is an advantage in the case of a potentiometer that we can change the length of the potentiometer wire and increase the accuracy of the instrument according to our requirement which is not possible in case of the voltmeter.

In voltmeter, the precision is fixed and we cannot change it.

The advantage of a potentiometer over the voltmeter is that the potentiometer doesn't draw any current from the circuit in which it is used for the measurement.

Whereas the voltmeter draws some amount of current in case of high voltages, which results in some errors in the measurements done using a voltmeter.
In voltmeter, there is always a loss of energy due to the internal resistance of the cell.

Note: We have seen the advantages of potentiometers over voltmeters, but the fact is that there are some disadvantages of potentiometers also. Some of them are:
a. Use of a potentiometer is inconvenient many times.
b. Area of the cross-section of potentiometer wire must be uniform which is practically not possible.
c. During the measurement, the temperature of potentiometer wire must be uniform and this is also difficult because of the flow of the current.