Explanation on Potentiometer

A potentiometer is a device to measure the potential difference across the series and circuits. Moreover, the potentiometer is often termed adjustable voltage dividers. The first potentiometer was invented by Thomas Edison, and he discovered the carbon potentiometer in the year 1872. Furthermore, the potentiometer operates on Principle and is applied in many fields. Music equipment, calibrations of systems, tuning, and angle transducer are some applications of potentiometers, to name a few.

Potentiometer principle and its applications to measure potential difference: Overview

A potentiometer is a three-terminal variable resistor whose impedance can be mechanically adjusted to manage the movement of electricity power. In a nutshell, a potentiometer is similar to the voltage divider. The significant difference is it can be controlled or, say, manually adjusted. Moreover, the potentiometer is also termed as pot-metre or pot in science. Potentiometers are made out of a variety of materials, comprising metal film, cermet, carbon composition, wire wound, and conductive plastic components.

• Principle- In simpler words, the Principle denotes, ”the potential drop over a portion of a cable with a uniform cross-section delivering a steady voltage is dependent on the distance of the cable.”

• Applications- There are several types of potentiometers; various potentiometers are used for different purposes. However, comparing the EMF of two cells, calibration of component, and measurement of internal resistance of a cell are some major purposes where the potentiometers are used readily.

Comparing EMF of two cells

Firstly, EMF is the electromotive force of a cell. The potentiometer compares the electromotive force (e.m.f.) of 2 cells to determine the internal resistance of cells. Moreover, it also measures the potential difference throughout resistors. Let us consider a wooden board. Two cables of copper ribbons are extended parallel to one another and connected to each other board. 

Furthermore, a cell should be placed between both ends, and its balancing length should be evaluated to obtain the emf of the cell. Since no current will flow first from the cell, this fall in potential throughout the length l of the potentiometer wire is equivalent to the emf of the cell. 

Other applications

There are endless applications of potentiometers. It can be applied in aspects related to tuning, audio applications, angle transducers, calibrations of systems. Two of them are as follows. 

• Angle transducer – A potentiometer can measure distances or angles while placing itself as an angle transducer.

• In audio applications- A (motorised) potentiometer is frequently used to adjust loudness. The dual potentiometer with a logarithmic taper on one side as well as an inverted logarithmic taper on either gang can be utilised for balancing adjustment. Faders are commonly used in commercial sound systems.

Types of potentiometer

The single-turn rotatory potentiometer, linear potentiometer, and digital photometers are three of the most abundantly used types of the potentiometer. 

• Rotatory Potentiometer: This potentiometer is employed for a variety of purposes, including an audio sound system (logarithmic taper). It has two terminals. The two input supply lines are connected to the resistor’s end in a potentiometer. Similarly, the slide connection on the output side of the resistor is adjusted to change the output voltage. 

• Linear Potentiometer: A straight resistor with two sides linked throughout the source voltage is used here. Across a track connected to the resistor, a slider connection could be slid just on the resistor. The linear potentiometer is similar to a rotary potentiometer, except that, rather than rotary movement, the moving contact is adjusted linearly on the resistor.

• Digital Potentiometer: The purpose of a digital potentiometer, also termed digital resistor, is similar to that of a traditional potentiometer. A resistor ladder, which is a succession of tiny resistors, is commonly used to do this. Instead of mechanical pressure, digital signals and switches are used. 

Conclusion

We learned that the potentiometer is a device that is used to measure the potential differences across series or circuits and other related aspects. We also learned the three major types of potentiometers, namely linear, rotatory and digital potentiometers. Moreover, comparing the EMF of two cells to find the measurement of internal resistance of the cell is the major application of this device.