Potentiometer: Learn its Types, Principle, Construction, Working, & Uses

The market offers a wide variety of resistors. Resistors come in a variety of sizes and forms and are used to control the current flow by either adding or removing resistance from the circuit. The most popular kind of resistor is the potentiometer. In the early stages of electronics research, a device called a potentiometer was created. Potential difference and metering are combined to form the word “potentiometer.”

We will explore the potentiometer’s principle, construction, working, uses, and a lot more in this Physics article.

Potentiometer

Potentiometer Definition: An electrical device known as a potentiometer monitors a cell’s internal resistance as well as its EMF (electromotive force). Additionally, it is utilized to contrast the EMFs of distinct cells. It is a device used to gauge the unknown voltage by contrasting it with the established voltage. It may also be utilized as a variable resistor in the majority of applications.

The potentiometer is a three-terminal variable resistor that may be manually adjusted. A resistive element has two terminals attached to its ends and a third terminal attached to a movable wiper. The resistance divider ratio is determined by the wiper’s position.

The fundamental operating principle of this is driven by the fact that the wire has a constant cross-sectional area and a constant current flowing through it. The decrease of the potential across any piece of the wire is precisely proportional to the length of the wire. Electric current flows if there is no potential difference between two nodes.

Types of Potentiometer

The following are the different types of potentiometer:

Rotary Potentiometer

• These potentiometers, in which the wiper travels in a circular motion, are the most prevalent kind.
• These potentiometers are mostly employed to provide a portion of circuits with a variable voltage source.
• The volume control on a radio transistor, where the turning knob regulates the current supply to the amplifier, is the greatest example of a rotary potentiometer.
• This type of potentiometer has two terminal connections where a semi-circular model with a constant resistance can be placed.
• It has a terminal in the center that is connected to the resistance via a sliding contact and a turning knob. Rotating the lever over the quarter resistance moves the sliding contact.
• The voltage of this may be acquired between the sliding and resistance contacts on two contacts.

Linear Potentiometer

• The wiper moves linearly in various varieties of potentiometers. Likewise called a slide pot, slider, or fader.
• This one rotates the resistor linearly with the sliding contact simply moving. The two terminals of the resistor are linked in series across the voltage source. On the resistor, a channel linked through it may be used to move a sliding contact.
• The resistor’s terminal is linked to one end of the circuit’s output, which is connected to the slide, and the other end, which is connected to the circuit’s other end, through another terminal.
• The voltage in a circuit is often calculated using this type of potentiometer.
• It is utilized in sound and music equalization mixing systems as well as to evaluate the internal resistance of battery cells.

Digital Potentiometer

• Digital potentiometers, also known as digiPots or variable resistors, are used with microcontrollers to regulate analog signals.
• These potentiometer types provide an adjustable o/p resistance based on digital inputs. These are also referred to as RDACs at times (resistive digital-to-analog converters).
• One switch that is linked to the o/p terminal of the digital potentiometer is included in each stage of the resistor ladder. The ladder step that is selected may be used to calculate the potentiometer’s resistance ratio.
• These actions are typically denoted, for example, by a bit value. 256 steps are represented by 8 bits.

Construction of Potentiometer

The potentiometer is made of a known EMF battery V and a long resistive wire L made of magnum or with constant. Driver cell voltage is the name of this voltage. Assuming this is a primary circuit configuration, attach the resistive wire L’s two ends to the battery terminals as illustrated below.

One end of the primary circuit is occupied by the terminal of a different cell (whose EMF E is to be measured), and the other end of the cell terminal is linked to any location along the resistive wire through a galvanometer G.

Working of Potentiometer

Currently, the wire used in potentiometers has a homogeneous cross-sectional area A and a high resistance. As a result, it faces consistent opposition along the whole wire. Usually, this potentiometer terminal that is connected to the high EMF cell, V, is referred to as the driving cell or the voltage source. Let I represent the potentiometer current and R represent the device’s complete blockage.

Using Ohm’s law, then

V=IR

Also, we know that,

Thus,

Since, and A are constant,

Thus,

where K is constant.

Therefore,

V=KL

Assume that the circuit is expanded as shown by adding cell E, which has a lower EMF than the driving cell. Suppose it is EMF, E. In the potentiometer wire, let’s say at length x, the potentiometer has now changed to E.

Since the potential difference is equal to zero when this cell is connected to the proper length (x) in the circuit shown above, no current will pass through the galvanometer. The galvanometer G, therefore, shows null detection. The length of the null point is therefore denoted by (x). You can fix the issue now that you know the constant K and the length x. We’ll be able to find the enigmatic EMF.

By considering that the first cell of the EMF, E1, and the second cell of the EMF, E2, both have null points at lengths and , it is possible to compare the EMF of the two cells.

Sensitivity of Potentiometer

The most un-potential variation that is identified with a potentiometer’s help is what is known as the potentiometer affectability. Its capacity to be affected is mostly dependent on the likelihood of a slope (K). The potential distinction that a potentiometer can detect is less when the potential slope esteem is low, and subsequently, the potentiometer’s affectability is greater. This allows the potentiometer affectability to increase for a given anticipated divergence by increasing the potentiometer’s length.

The following factors can also lead to an expansion of potentiometer affectability.

• By lengthening the potentiometer
• By reducing the circuit’s internal current flow with a rheostat

Uses of Potentiometer

The following are uses of potentiometer:

• Voltage divider

By using the potentiometer as a voltage divider, a set input voltage may be applied across its two ends to produce a manually adjustable output voltage at the slider.

• Sound Control

One of the most popular applications for contemporary low-power sliding potentiometers is as audio control equipment. Sliding pots and rotating potentiometers are used to change the volume, attenuate frequencies, and control other aspects of audio signals.

• Television

Potentiometers for televisions were used to regulate the brightness, contrast, and colour response of the images. The vertical hold setting was adjusted with a potentiometer.

• Transducers

The measurement of displacement is one of the most popular uses. The sliding element on the potentiometer is attached to the moveable body to measure its displacement.

A concise overview of a potentiometer is what this article is all about. We trust that you now have a clearer grasp of this data. Check out the Testbook app if you have any questions about fascinating physics terminology. You could learn more by taking plenty of practice tests and studying from well-curated written notes. The app is compatible with all versions of Android on the phone. Install the Testbook App immediately!