Let’s see the Difference Between Potentiometer And Voltmeter for class 12th physics, IITJee, AIEEE, and CPMT Exams.
Difference Between Potentiometer And Voltmeter Class 12
|1.||Potentiometer resistance is infinite.||Voltmeter resistance is high but finite.|
|2.||It does not draw any current from the source of known e.m.f.||It draws some current from the source of e.m.f.|
|3.||The potential difference measured by it = actual potential difference.||The potential difference is measured by it. < actual potential difference.|
|4.||Potentiometer sensitivity is high.||Voltmeter sensitivity is low.|
|5.||It is a versatile instrument.||It measures only e.m.f. or potential difference.|
|6.||A potentiometer is based on the zero deflection method.||A voltmeter is based on the deflection method.|
|7.||Fixed or installed device.||Portable device.|
The ideal apparatus of infinite resistance based on the null deflection method and used to measure unknown potential differences is known as a potentiometer.
Principle of Potentiometer
The unknown e.m.f. or potential difference is compared with known variable potential produced on the potentiometer wire. The current detector for this purpose is taken as a galvanometer.
In zero deflection position:
Unknown potential difference = Known potential difference
- A potentiometer is said to be more sensitive if it measure a small potential difference more accurately.
- The sensitivity of potentiometer is assessed by its potential gradient. The sensitiivity is inversivly proportional to the potential gradient i.e. lower potential gradient higher will be the sensitivity and vice versa.
- In order to increase the sensitivity of potentiometer:
(A) The registance in the primary circuit has to be increased and current have to be decreased.
(B) The length of the potentiometer wire will have to be increased so, that the length may be measured more accurately.
Standardization of Potentiometer
The process of determining potential gradients experimentally is known as the standardization of the potentiometer.
Circuit Diagram of Potentiometer
Applications of Potentiometer
- To determine the internal registance of a primary cell like Denial cell etc.
- To compare e.m.f. of two cells.
- To compare two small registance.
- To caliberate Ameter and Voltmeter.
- To determine thermo e.m.f.
- To standardize the potentiometer.