Table of Contents
A potentiometer is a three-terminal resistor with a sliding or rotating contact that acts as a variable voltage divider. When only one terminal, one end, and the wiper, it functions as a variable resistor or rheostat. A potentiometer is a measuring instrument that is essentially a voltage divider used to measure electric potential (voltage); the component is an implementation of the same principle, hence its name. Potentiometers are commonly used to control electrical devices such as audio volume controls. Potentiometers with a mechanism can be used as position transducers, such as in a joystick. Potentiometers are rarely used to control significant power (more than a watt) directly because the power dissipated in the potentiometer is comparable to the power in the controlled load.
When the potentiometer is understood, the operation of the potentiometer can be explained. It is a three-terminal resistor with sliding or rotating contacts that act as a voltage divider. To be used as a rheostat or variable resistor, the potentiometer should only have two terminals: one end and the wiper. The following terms are used to describe different types of potentiometers:
- Slider pot or slide pot: You can adjust this by sliding the wiper right or left with your finger or thumb.
- Thumb wheel pot or thumb pot: This is a small rotating potentiometer that can be adjusted infrequently with the help of a small thumb wheel.
- Trimmer pot or trim pot: This is a one-time adjustment for fine-tuning an electric signal.
A potentiometer is a device that is used to compare the electromotive force of two cells, to measure the potential difference between two points in a given circuit, and to measure the internal resistance of a cell. Potentiometers are widely used in the production of electronic equipment to provide a means of adjusting electronic circuits as appropriate results are obtained.
Overview
A potentiometer is simply a long piece of uniform wire connected to a standard cell. The long wire is cut into several pieces, which are placed side by side and connected at the ends with a thick metal strip in the actual design. A variable resistance (rheostat) connected to the circuit can be used to control the current flowing through the wire. To measure the potential difference, the resistance can be manually changed. The potential difference between any two points in a circuit represents the amount of work done in moving the charge from one point to the other. When there is a potential difference, current flows in the circuit. The potentiometer is a device used to measure unknown voltages by comparing them to known voltages. It can be used to calculate the emf and internal resistance of a specific cell, as well as to compare the emf of different cells. The potentiometer employs the comparative method. A potentiometer provides a more accurate reading.
A potentiometer is a device that detects potential differences in a circuit. As we know, the potential difference is the amount of work required to move a charge from one location to another. When a potential difference exists in a circuit, current flows through it. Volts are the unit of measurement for Potential Difference. A voltmeter can be used to measure a circuit’s potential difference. Now we will look at the Potentiometer Working Principle and Potentiometer Applications.
A potentiometer is a three-terminal variable resistor. A resistor, which is a bundle of resistance, is a common component in an electric circuit. Resistors come in a variety of shapes and sizes and are frequently used to regulate current flow by adding or subtracting resistance from the circuit. Aside from these two characteristics, namely size and shape, resistors are classified as fixed or variable. A fixed resistor, as the name implies, has a fixed resistance value, whereas a variable resistor has a resistance value that varies over a defined range.
Working Principle of Potentiometer
The potentiometer is made up of L, along the resistive wire, and V, a battery with a known EMF whose voltage is known as driver cell voltage. Assume a primary circuit configuration by connecting the ends of L to the battery terminals. The primary circuit is connected to the cell whose EMF E is to be measured, and the secondary circuit is connected to the galvanometer G. It is assumed that this circuit is a secondary circuit.
The working principle is based on the potential across any portion of the wire being directly proportional to the length of the wire with a uniform cross-sectional area and constant current flow. The following is the derivation of used to explain the working principle of a potentiometer:
V = IR
Where I denotes current, R denotes total resistance, and V denotes voltage.
R = ρL/A and V = I (pL/A) are now equal.
Where ρ denotes resistivity and A denotes cross-sectional area.
For a rheostat, with and A constants, I am also constant.
Hence,
Lρ/A = K
V = KL
E = Lρx/A =Kx
Where x is the length of the potentiometer wire, E is the cell with the lower EMF, and K is the constant.
The galvanometer has null detection because the potential difference is zero (0) and there is no current flow. As a result, x is defined as the length of the null point. Finally, using K and x, the unknown electromotive force can be determined:
E = Lρx/A = Kx
Because the EMF here includes two cells, let L1 and L2 be the null point lengths of the first and second cells, respectively, with EMF E1 E1 and EMF E2.
So,
E1/E2 = L1/L2
Types of Potentiometer
Although all potentiometers have the same basic working principle and construction, they differ in the geometry of the moving terminals. The wiper on the majority of potentiometers rotates on an arc-shaped resistive material. Nonetheless, the wiper in some other types of potentiometers moves linearly on a straight resistive strip. Potentiometers are classified into two types based on the concept of the resistive strip: rotary and linear.
Rotary Potentiometer: This type of pot has a wiper that rotates across two terminals to vary the potentiometer’s resistance. Rotary potentiometers are classified as follows:
One-turn pot: The wiper’s single revolution is approximately 360 degrees or 3/4 of a full turn.
Potentiometers can access multiple turns if a wiper is in spiral or helix form, or if a special worm gear is used.
Concentric pot: With concentric shafts, the two potentiometers are individually adjusted. This allows you to incorporate two controls into a single unit.
A servo pot is a motorised container used to control and modify a motor.
The linear potentiometer functions similarly to the rotary potentiometer. However, there is linear resistance rather than circular resistance. Linear Potentiometers are further classified as follows:
The slide pot is constructed of conductive plastic. The fader is another name for a single linear slider potentiometer.
The Multi-turn Slide: The multi-turn slide is made up of a spindle that activates the linear potentiometer’s wiper.
Dual Slide Pot: This potentiometer can be used to control two potentiometers in parallels, such as a dual slide or a single slider.
A motorised fader is one that is controlled automatically by a servo motor.
Application of Potentiometer
Audio control: Both linear and rotary potentiometers are used to control audio equipment in order to change the volume and other audio-related signals.
Television: They are used to control the brightness, colour response, and contrast of the image.
Potentiometers are used as position feedback devices known as servomechanisms in order to create a closed-loop control.
Transducers: Because they produce large output signals, they are used in the design of displacement transducers.
FAQs
What is the purpose of a potentiometer?
A position sensor is a potentiometer. They can measure displacement in any direction. Linear potentiometers measure displacement linearly, whereas rotary potentiometers measure rotational displacement.
What is a potentiometer and how does it work?
The potential dropped across a segment of a wire of uniform cross-section carrying a constant current is directly proportional to its length, according to the principle of a potentiometer. A potentiometer is a simple device for measuring electrical potentials (or compare the e.m.f of a cell).
