Difference between Potentiometer and Voltmeter

Discover the key differences between Potentiometer and Voltmeter in this informative article by Edukar. Learn about the functions, uses, and advantages of each device to gain a better understanding of their unique features and applications. Whether you are an electronics enthusiast or a curious learner, this article is sure to provide you with valuable insights into these fundamental instruments.

Potentiometers and voltmeters are two electronic devices commonly used in various applications to measure electrical properties. Potentiometers and voltmeters play significant roles in electronic engineering, physics, and other technical fields that deal with electrical and electronic components. Both instruments may seem similar, but they serve different purposes, and their constructions and working principles are unique.

Potentiometer

Potentiometers are variable resistors that allow users to adjust the resistance by varying the position of the wiper on a resistive element. They have three terminals, with two outer terminals connecting to the resistive element and the third connecting to the movable wiper. Potentiometers have a wide range of applications, including volume controls on audio equipment, dimmer switches on lighting systems, and the control of robotic actuators.

Construction and Components of Potentiometer

Potentiometers come in different shapes and sizes, but their basic construction is similar. They consist of a resistive element, a wiper, and three terminals. The resistive element is typically made of a carbon composition, conductive plastic, or a wire-wound element. The wiper is a movable contact that slides along the resistive element. The three terminals are the input, output, and the wiper terminal. The input and output terminals connect to the ends of the resistive element, while the wiper terminal connects to the wiper.

Working Principle of Potentiometer

The potentiometer’s working principle is based on the relationship between the resistive element’s length and resistance. When a voltage is applied across the input and output terminals, a voltage gradient is formed across the resistive element. As the wiper is moved along the resistive element, the resistance between the wiper and the output terminal changes, altering the output voltage.

The output voltage is a fraction of the input voltage and depends on the position of the wiper along the resistive element. The resistance between the wiper and output terminal can be calculated using Ohm’s Law, where V is the voltage, R is the resistance, and I is the current flowing through the circuit.

Applications of Potentiometer

Potentiometers have a wide range of applications, including:

• Audio equipment volume controls
• Lighting systems dimmer switches
• Robotic actuators
• Thermostats
• Speed controllers
• Tuning circuits
• Balance and level controls

Voltmeter

A voltmeter is an instrument used to measure the voltage difference between two points in a circuit. Voltmeters come in two types, analog and digital. Analog voltmeters use a pointer or a moving coil to indicate the voltage on a calibrated scale. Digital voltmeters convert the voltage to a digital value and display it on a screen. Voltmeters are essential tools for electrical engineers and technicians, allowing them to measure voltage accurately and troubleshoot electrical problems.

Construction and Components of Voltmeter

Voltmeters consist of a sensitive galvanometer, a resistor, and a series of switches. The galvanometer is connected in series with a resistor, forming a voltage divider circuit. The switches allow the user to select the range of the voltmeter, adjusting the resistance of the circuit to match the voltage being measured. Analog voltmeters have a scale attached to the galvanometer, while digital voltmeters display the voltage value on a screen.

Working Principle of Voltmeter

The voltmeter’s working principle is based on Ohm’s Law, which states that the current flowing through a resistor is directly proportional to the voltage difference across it. When a voltage is applied to the circuit being measured, the current flows through the resistor and the galvanometer. The current flowing through the galvanometer creates a magnetic field that interacts with a permanent magnet, causing the pointer to move on an analog voltmeter or generating an electrical signal on a digital voltmeter. By selecting the proper range and measuring the current, the voltmeter can accurately measure the voltage difference between two points in a circuit.

Types of Voltmeters

There are two types of voltmeters: analog and digital. Analog voltmeters use a mechanical movement to display the voltage reading, while digital voltmeters use digital displays to show the voltage value.

Applications of Voltmeter

Voltmeters have a wide range of applications, including:

• Troubleshooting electrical circuits
• Testing batteries and power supplies
• Measuring the voltage of electronic components
• Monitoring the voltage in power distribution systems
• Testing the electrical systems in automobiles

Differences between Potentiometer and Voltmeter

Potentiometer	Voltmeter
Measures potential difference by comparing an unknown voltage with a known voltage.	Measures potential difference directly in a circuit.
Consists of a variable resistor and a galvanometer.	Consists of a sensitive voltmeter and is used to measure voltage in a circuit.
Can be used to find internal resistance of a cell or EMF of a cell.	Can’t be used to find the internal resistance of a cell or EMF of a cell.
Can be used to find the value of an unknown resistance.	Can’t be used to find the value of an unknown resistance.
Used in the calibration of voltmeters and ammeters.	Used to measure voltage across a particular component in a circuit.
Used for accurate measurement of EMF and potential difference.	Used for accurate measurement of voltage in a circuit.
Can be used in the construction of Wheatstone bridge circuits.	Not used in the construction of Wheatstone bridge circuits.
Has a variable resistance which can be adjusted to get the desired voltage.	Has a fixed resistance and measures voltage across a component.
Has a high internal resistance compared to voltmeters.	Has a low internal resistance compared to potentiometers.
Used in the calibration of pH meters, thermocouples and thermometers.	Not used in the calibration of pH meters, thermocouples and thermometers.

Summary

Potentiometers and voltmeters are two essential electronic instruments used to measure electrical properties. Potentiometers are variable resistors used to vary the resistance in a circuit, while voltmeters are used to measure the voltage difference between two points in a circuit. Despite having some similarities, such as the use of resistive elements, their constructions and working principles are different. Understanding the differences between potentiometers and voltmeters is essential for anyone working with electronic components and circuits.

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