Potentiometer Working - Definition, Types, Application, FAQs

Edited By Vishal kumar | Updated on Jul 02, 2025 04:52 PM IST

A potentiometer is an instrument used to measure the EMF, resistance, and voltage. It works based on the principle of balancing potential differences without drawing electric current. A potentiometer gives highly accurate measurements. In this article, we are going to discuss what is potentiometer class 12, the working principle of potentiometer, potentiometer working, the internal resistance of a cell, types of potentiometer, and application of potentiometer.

This Story also Contains

What is a Potentiometer Class 12?
Working Principle Of Potentiometer and Potentiometer Working
Internal Resistance of the Cell
Types of Potentiometer Based on Adjustment Mechanism
Types of Rotating Potentiometers
Types of Linear Potentiometer
Application of Potentiometer

Potentiometer Working - Definition, Types, Application, FAQs

What is a Potentiometer Class 12?

In physics, a potentiometer is an instrument that is made up of three terminal resistors that have sliding or rotating contact that forms a voltage divider and this voltage driver is also adjustable. The potentiometer is used as the rheostat (also known as variable resistor) when it has two terminals that contain one end and a wiper. In short, these potentiometers are also called “pots”. The potentiometer diagram is given below.

Rotation in the potentiometer digrame

Working Principle Of Potentiometer and Potentiometer Working

The potentiometer contains a long resistive wire L, and an EMF battery V. This voltage V is also called driver cell voltage. Consider a primary circuit that is connected to the emf cell. The other end of the circuit is connected to the G, galvanometer. This circuit is considered to be a secondary circuit.

The potentiometer working is based on the potential across the wire and the length of the wire which has a uniform area cross-section and constant current flow that shares a proportionality relation. In short, the principle behind the potentiometer working can be explained as the potential across the wire is directly proportional to the length of the wire. This can be expressed as

$$V=I R$$

Where I denotes the current flow, R denotes the total resistance of the circuit, V denotes the voltage

$$R=\frac{\rho L}{A}$$

$$V=I \frac{\rho L}{A}$$

Where,

$\rho$ denotes the resistivity of the material
$A$ is used to denote the area cross-section

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When $\rho$ and area are constant, then $I$ current also becomes constant for the rheostat.

$$
K V=K L E
$$

And

$$\frac{L \rho x}{A}=K x$$

Where,

$x$ refers to the length of the potentiometer wire
$E$ refers to the low EMF of a cell
$K$ is a constant

When the potential difference between the ends is zero, the galvanometer G shows null detection. This denotes that the flow of current in the circuit is also zero. Here, the x is considered to be the length of the null point. Now, unknown EMF is found from the following formula,

$$
E=K x=\frac{L \rho x}{A}
$$

As the EMF has two cells, consider $L_1$ to be the length of the null point of EMF cell $E_1$ and $L_2$ to be the length of the null point of EMF cell

$$
\frac{E_1}{E_2}=\frac{L_1}{L_2}
$$

Internal Resistance of the Cell

A cell having unknown resistance (r) is connected in series with a resistance box and key $K_2$. The wires are connected in parallel with the cell and resistance box. A galvanometer is connected. Open circuit EMF of the cell is measured when the $K_2$ is opened as there is no current in the circuit.

internal resistance of the cell

$$
E=k \cdot L_1
$$

When $K_2$ is closed, the current flows through the resistance box and internal resistance, hence terminal voltage is

$$
V=k \cdot L_2
$$

We know that $E=V+I r$

Substitute $I=\frac{V}{R}$, we get

$$
E=V+\frac{V}{R} \cdot r
$$

Solving for r,

$$
r=R \cdot\left(\frac{E}{V}-1\right)
$$

Substituting $\frac{E}{V}=\frac{L_1}{L_2}$ in the equation,

The internal resistance of the cell, $$
r=R \cdot\left(\frac{L_1}{L_2}-1\right)
$$

Types of Potentiometer Based on Adjustment Mechanism

Let us see the different types of potentiometers and also discuss them in detail.

Slider potentiometer (also known as slide potentiometer):
This type of potentiometer is adjustable by sliding the wiper in the right or left direction.
Thumbwheel potentiometer(also known as thumb potentiometer):
This type of potentiometer is adjustable with a small thumbwheel.
Trimmer potentiometer (also known as trim potentiometer):
This type of potentiometer is adjustable by the fine-tuning of some electric signals.

Types of potentiometers based on operation are linear potentiometers and rotating potentiometers.

Types of Rotating Potentiometers

Concentric potentiometer
Single turn potentiometer
Servo potentiometer

Concentric potentiometer

Two different potentiometers are adjustable individually by the concentric shafts. These types of potentiometers are used as control volume in the radios of old cars.

Single-turn potentiometer

This type of potentiometer is adjustable up to 270 degrees with the help of a single rotation. These types of potentiometers are used to control the resolution in a single rotation.

Servo potentiometer

The Servo potentiometer can be adjusted by servo motors automatically. These types of potentiometers are used in the volume control of remote control audio equipment.

Related Topics,

Types of Linear Potentiometer

Multi-turn slide Potentiometer
Slide Potentiometer
Dual slide Potentiometer

Multi-turn slide Potentiometer

In the construction of a multi-turn slide Potentiometer, a spindle is used.

Slide Potentiometer

In the construction of the slide Potentiometer, the high-quality fader is used. This potentiometer is used to measure distance.

Dual slide potentiometer

Dual slide Potentiometers are used to control single and dual sliders which are connected in parallel.

Application of Potentiometer

Linear and rotary Potentiometer is used in controlling the audio equipment to adjust the volume of the audio signals.
The potentiometer in televisions is used to control the brightness of the picture, colour, and so on.
The potentiometers are also used in motion control in position feedback devices like servo motors.
The potentiometers used in transducers are used to design the displacement transducers.
The potentiometers are used as control volume in the radios of old cars.

Also read:

Frequently Asked Questions (FAQs)

1. What is the principle of potentiometer or on what principle does the potentiometer work?

The principle behind the potentiometer working can be explained as the potential across the wire is directly proportional to the length of the wire. This can be expressed as V=IR. In detail, The potentiometer working is based on the potential across the wire and the length of the wire which has uniform area cross section and constant current flow shares a proportionality relation.

2. Define potentiometer or what does a potentiometer mean?

A potentiometer is an instrument which is made up of three terminal resistors in which has sliding or rotating contact that forms a voltage divider and this voltage driver is also adjustable. The potentiometer is used as the rheostat (also known as variable resistor), when it has two terminals that contain one end and wiper. In short, these potentiometers are also called “pots”.

3. How does a multi turn potentiometer work?

In the construction of multi turn slide Potentiometer, a spindle is used. A wheel is attached to the spring which changes the linear position into a variable one.

4. Write one application of potentiometer

Linear and rotary Potentiometer is used in controlling the audio equipment to adjust the volume of the audio signals.
The potentiometer in televisions are used to control the brightness of the picture, color, and so on.
The potentiometers are also used in the motion control in position feedback devices like servo motors.
The potentiometers used in transducers are used to design the displacement transducers.
The potentiometers are used as control volume in the radios of old cars.

5. What is the null detector definition?

When the potential difference between the ends is zero, the galvanometer G shows null detection. This denotes that the flow of current in the circuit is also zero. The instrument is used to detect the zero current condition of a circuit, where the voltage between the endpoints are the same.

6. What is known as a resistive potentiometer?

The potentiometer is constructed to be adjustable with a variable resistor made of 3 different terminals. Two terminals in that are connected such that they are connected to the opposing ends of the resistive element.

7. Name some of the types of potentiometer:

There are a lot of potentiometers in practice and each vary from their uses and applications. Some of the potentiometer is listed below:

Multi turn slide Potentiometer
Slide Potentiometer
Dual slide Potentiometer
Thumbwheel potentiometer(also known as thumb potentiometer)
Trimmer potentiometer (also known as trim potentiometer)
Concentric potentiometer
Single turn potentiometer
Servo potentiometer

8. What are the main types of potentiometers?

The main types of potentiometers are linear and rotary. Linear potentiometers have a sliding contact that moves in a straight line, while rotary potentiometers have a rotating contact. Each type has specific applications based on their design and functionality.

9. How can a potentiometer be used as a voltage divider?

When used as a voltage divider, a potentiometer's fixed terminals are connected across a voltage source, and the wiper acts as the output. By adjusting the wiper position, you can "divide" the input voltage and obtain a variable output voltage between zero and the input voltage.

10. How does the resolution of a potentiometer affect its performance?

Resolution refers to the smallest change in position that can be detected or set. Higher resolution potentiometers allow for more precise adjustments, which is crucial in applications requiring fine control. Digital potentiometers often have higher resolution than their analog counterparts.

11. How does a potentiometer differ from a rheostat?

While both are variable resistors, a potentiometer has three terminals and is typically used for voltage division, whereas a rheostat has two terminals and is used for current control. Potentiometers are more versatile and can be used in a wider range of applications.

12. What is the difference between a single-turn and a multi-turn potentiometer?

A single-turn potentiometer can rotate through a maximum of 360 degrees, while a multi-turn potentiometer can rotate through multiple revolutions (typically 3, 5, or 10 turns). Multi-turn potentiometers offer finer adjustment and higher resolution but are generally more expensive.

13. How does a linear potentiometer work?

A linear potentiometer has a resistive strip and a sliding contact (wiper) that moves along it. As the wiper moves, it changes the resistance between itself and the ends of the strip, allowing for a linear change in resistance or voltage output relative to the wiper's position.

14. What is the principle behind a rotary potentiometer?

A rotary potentiometer operates on the same principle as a linear potentiometer but uses a circular resistive track instead of a straight one. The wiper rotates around the track, changing the resistance or voltage output based on its angular position.

15. What is a potentiometer and how does it work?

A potentiometer is a variable resistor with three terminals. It works by adjusting a sliding contact (wiper) along a resistive element, changing the resistance between the wiper and the ends of the element. This allows for precise control of voltage or current in a circuit.

16. What is the wiper in a potentiometer?

The wiper is the movable contact in a potentiometer that slides along the resistive element. It acts as the adjustable terminal, allowing the user to vary the resistance or voltage output by changing its position relative to the fixed terminals.

17. What is the significance of the taper in a potentiometer?

The taper of a potentiometer refers to the relationship between the wiper position and the resulting resistance or voltage output. Common tapers include linear (even change), logarithmic (faster change at one end), and inverse logarithmic (faster change at the other end). The taper is chosen based on the specific application requirements.

18. What is the purpose of a trimmer potentiometer?

A trimmer potentiometer, or "trimmer," is a small, precision potentiometer used for fine-tuning or calibration in electronic circuits. It's typically adjusted once during manufacturing or servicing and is not meant for frequent user adjustments.

19. How do conductive plastic potentiometers differ from wirewound types?

Conductive plastic potentiometers use a resistive element made of plastic with conductive particles, while wirewound types use a coil of resistive wire. Conductive plastic types generally offer smoother operation, better resolution, and longer life, but may be less stable over time compared to wirewound potentiometers.

20. How does the number of turns in a multi-turn potentiometer affect its precision?

More turns in a multi-turn potentiometer allow for finer adjustments and higher precision. For example, a 10-turn potentiometer provides ten times the resolution of a single-turn potentiometer, allowing for more accurate settings and smoother control.

21. What is the purpose of a dual-gang potentiometer?

A dual-gang potentiometer consists of two potentiometers mechanically linked to operate simultaneously. They are often used in stereo audio equipment to control left and right channels together, or in applications requiring simultaneous adjustment of two related parameters while maintaining a fixed relationship between them.

22. How does the concept of "resolution" differ between analog and digital potentiometers?

In analog potentiometers, resolution is limited by factors like the smoothness of the resistive element and the precision of the wiper movement. Digital potentiometers have discrete steps, with resolution determined by the number of bits (e.g., 8-bit = 256 steps). Digital potentiometers often offer higher and more consistent resolution, especially in multi-turn configurations.

23. How does temperature affect a potentiometer's performance?

Temperature changes can affect a potentiometer's resistance and linearity. Most potentiometers have a temperature coefficient that describes how much the resistance changes per degree of temperature change. High-quality potentiometers are designed to minimize these effects.

24. How does the power rating of a potentiometer affect its use in a circuit?

The power rating determines the maximum amount of power the potentiometer can safely dissipate without damage. Exceeding this rating can cause overheating, changes in resistance, or failure. It's crucial to choose a potentiometer with an appropriate power rating for the intended application.

25. How does the concept of "backlash" apply to potentiometers?

Backlash in potentiometers refers to the small amount of play or looseness in the mechanical linkage between the shaft and the wiper. It can cause a slight delay or inconsistency when changing direction of adjustment. Low backlash is crucial in applications requiring precise bidirectional control or positioning.

26. How does the concept of "thermal noise" apply to potentiometers?

Thermal noise, also known as Johnson-Nyquist noise, is the electronic noise generated by the thermal agitation of charge carriers inside an electrical conductor. In potentiometers, this manifests as a small, random fluctuation in voltage across the resistive element. While generally small, it can be significant in high-precision or low-signal-level applications.

27. How does the concept of "absolute maximum rating" apply to potentiometers?

The absolute maximum rating specifies the highest voltage or current that can be applied to a potentiometer without causing permanent damage. Exceeding these ratings, even momentarily, can lead to immediate failure or reduced lifespan. It's crucial to design circuits that keep the potentiometer within these limits under all operating conditions.

28. What is a digital potentiometer and how does it differ from an analog one?

A digital potentiometer uses electronic switches to simulate the function of an analog potentiometer. It offers precise digital control, programmability, and often higher resolution. Unlike analog potentiometers, digital ones don't have mechanical wear and can be controlled by microprocessors.

29. How does the resistance range of a potentiometer affect its sensitivity?

The resistance range affects how much the output changes for a given movement of the wiper. A wider range allows for more precise control over a larger span of values, while a narrower range provides finer control within a smaller span. The choice depends on the specific application requirements.

30. What is the importance of linearity in potentiometers?

Linearity refers to how closely the potentiometer's output follows a straight-line relationship with the wiper position. High linearity is important in applications requiring precise, proportional control. Non-linear potentiometers may be preferred in audio applications to match human hearing characteristics.

31. What is the function of a potentiometer in a voltage regulator circuit?

In a voltage regulator circuit, a potentiometer can be used to adjust the output voltage. By connecting the potentiometer as a variable voltage divider in the feedback loop, it allows fine-tuning of the regulated voltage to the desired level.

32. How does the contact resistance of a potentiometer affect its performance?

Contact resistance is the resistance between the wiper and the resistive element. Lower contact resistance leads to more accurate and stable performance. High contact resistance can cause noise, inconsistent readings, and reduced overall accuracy of the potentiometer.

33. What is the difference between a logarithmic and a linear potentiometer taper?

A linear taper provides a consistent change in resistance or voltage for each unit of wiper movement. A logarithmic taper, on the other hand, provides a non-linear change, with faster changes at one end of the range. Logarithmic tapers are often used in audio applications to match human hearing characteristics.

34. What is the purpose of a center tap in a potentiometer?

A center tap is an additional connection at the midpoint of the potentiometer's resistive element. It provides a fixed reference point and allows the potentiometer to be used in applications requiring balanced or differential outputs, such as audio balance controls or certain types of sensors.

35. How does the wiper material affect the lifespan of a potentiometer?

The wiper material significantly impacts the potentiometer's durability and performance over time. Materials like precious metals (gold, platinum) or certain alloys provide better wear resistance and lower contact resistance, leading to a longer lifespan and more stable performance compared to less durable materials.

36. What is the significance of the "end resistance" in a potentiometer?

End resistance refers to the small resistance that remains when the wiper is at either extreme end of its travel. It's important in applications requiring very low minimum resistance or precise voltage division. Lower end resistance generally indicates better quality and more precise control.

37. How does a potentiometer's resistance tolerance affect circuit performance?

Resistance tolerance indicates how much the actual resistance may deviate from the nominal value. Tighter tolerances (e.g., ±1% vs ±10%) ensure more predictable and consistent performance in the circuit. In precision applications, potentiometers with low tolerance are crucial for accurate control and measurements.

38. How does the concept of "absolute linearity" differ from "independent linearity" in potentiometers?

Absolute linearity measures how closely the potentiometer's actual output matches an ideal straight line from zero to full scale. Independent linearity measures the deviation from the best-fit straight line, which may not necessarily pass through the zero and full-scale points. Independent linearity often appears better and is more commonly specified.

39. What is the role of a potentiometer in a Wheatstone bridge circuit?

In a Wheatstone bridge circuit, a potentiometer can be used as one of the resistive elements to balance the bridge. By adjusting the potentiometer, the bridge can be precisely balanced, allowing for accurate measurements of unknown resistances or small changes in resistance, such as in strain gauge applications.

40. How does the "noise" in a potentiometer affect its performance in sensitive circuits?

Potentiometer noise refers to small, unwanted variations in resistance as the wiper moves. This can introduce fluctuations in voltage or current in sensitive circuits. High-quality potentiometers with low noise characteristics are essential in applications like audio equipment or precision measurement devices to maintain signal integrity.

41. What is the purpose of a "dead band" in some potentiometers?

A dead band is a intentional region of no change in the potentiometer's output, typically near the center of its range. This feature is useful in applications where a neutral or rest position is needed, such as in joysticks or certain control systems, to prevent unintended small movements from affecting the output.

42. What is the significance of the "wiper current rating" in a potentiometer?

The wiper current rating specifies the maximum current that can safely flow through the wiper contact. Exceeding this rating can cause damage to the wiper, leading to poor contact, increased noise, or complete failure. It's particularly important in applications where the potentiometer is used for current control rather than just voltage division.

43. What is the purpose of a "non-linear" potentiometer taper?

Non-linear tapers, such as logarithmic or exponential, provide a non-uniform change in resistance or voltage output relative to wiper position. These are used in applications where a non-linear control response is desired, such as in audio volume controls where they better match human perception of loudness changes.

44. How does the "temperature coefficient of resistance" affect a potentiometer's performance?

The temperature coefficient of resistance (TCR) indicates how much the potentiometer's resistance changes with temperature. A low TCR is desirable for stable performance across varying temperatures. In precision applications or extreme environments, choosing a potentiometer with a suitable TCR is crucial for maintaining accuracy.

45. What is the role of a potentiometer in calibrating sensors?

Potentiometers are often used to calibrate sensors by adjusting offset and gain. For example, in a temperature sensor circuit, one potentiometer might set the zero point (offset), while another adjusts the scale factor (gain). This allows for fine-tuning the sensor's output to match specific requirements or to compensate for component variations.

46. How does the concept of "virtual ground" relate to potentiometer applications?

A virtual ground is a point in a circuit that behaves like ground (0V) but may not be directly connected to it. Potentiometers can be used to create a virtual ground in circuits that require a reference point between two voltage levels. This is particularly useful in single-supply op-amp circuits or in creating bipolar supplies from a single voltage source.

47. What is the significance of "wiper bounce" in potentiometer performance?

Wiper bounce refers to momentary loss of contact between the wiper and the resistive element as the potentiometer is adjusted, especially at high speeds. This can cause noise or intermittent operation in sensitive circuits. High-quality potentiometers are designed to minimize wiper bounce for smoother, more reliable operation.

48. How does the concept of "loading effect" apply to potentiometers in voltage divider circuits?

The loading effect occurs when the circuit connected to the potentiometer's output draws current, affecting the voltage division. This can cause the output voltage to be lower than expected. To minimize this effect, the load resistance should be much higher than the potentiometer's resistance, or a buffer amplifier can be used.

49. What is the purpose of a "multi-gang" potentiometer?

A multi-gang potentiometer consists of multiple potentiometers mechanically linked to operate together. They are used in applications requiring simultaneous control of multiple circuit parameters, such as stereo audio systems (controlling left and right channels) or RGB color mixing in lighting control systems.

50. How does the "power law" taper differ from logarithmic and linear tapers in potentiometers?

The power law taper follows a mathematical power function, offering a compromise between linear and logarithmic tapers. It provides a more gradual change in the middle range compared to a linear taper, but not as extreme as a logarithmic taper. This can be useful in applications requiring a balance between fine control and wide range adjustment.

51. What is the role of a potentiometer in motor speed control circuits?

In motor speed control circuits, a potentiometer can be used to adjust the voltage or current supplied to the motor, thereby controlling its speed. It may be part of a voltage divider to set a reference voltage for a control circuit, or it might directly control the current in a simple DC motor circuit.

52. What is the purpose of a "membrane potentiometer"?

A membrane potentiometer is a thin, flexible potentiometer that uses pressure to create electrical contact between conductive layers. They are used in applications requiring a low-profile or flexible interface, such as touch-sensitive controls in electronic devices or position sensing in automotive applications.

53. What is the significance of "end-to-end resistance" in potentiometer specifications?

End-to-end resistance is the total resistance measured between the two fixed terminals of the potentiometer. This value is important for circuit design as it determines the current flow and power dissipation in the potentiometer. It also affects the resolution and sensitivity of the potentiometer in voltage divider applications.

54. How does a "digital potentiometer" handle the concept of "wiper position"?

In a digital potentiometer, the wiper position is represented by a digital value stored in memory. This value determines which of the discrete resistive steps is selected to create the equivalent of a wiper position. The position can be changed through digital commands, often via protocols like SPI or I2C, allowing for precise and programmable control.

55. What is the role of a potentiometer in analog-to-digital converter (ADC) circuits?

In ADC circuits, potentiometers can be used to adjust reference voltages, set input ranges, or calibrate the converter. For example, a potentiometer might be used to fine-tune the full-scale voltage reference of an ADC, ensuring accurate conversion across the desired input range.