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Difference Between Potentiometer and Voltmeter for JEE Main 2024

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Last updated date: 29th May 2024
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What is Potentiometer and Voltmeter: Introduction

To explain potentiometer and voltmeter: A potentiometer, also known as a variable resistor, is a three-terminal device used to divide voltage in a circuit. It consists of a resistive element and a sliding contact, allowing the user to adjust the output voltage by changing the position of the contact along the resistive element. Potentiometers are commonly used for volume control in audio devices, as well as for calibrating and adjusting electrical equipment. On the other hand, a voltmeter is a measuring instrument specifically designed to measure the voltage in a circuit. It typically has a high input impedance to minimize loading effects and provides accurate voltage readings across a wide range. Voltmeters are widely used in electrical and electronic circuits to monitor voltage levels and ensure proper functioning of devices and systems. Let’s further know about them in detail. 


Category:

JEE Main Difference Between

Content-Type:

Text, Images, Videos and PDF

Exam:

JEE Main

Topic Name:

Difference Between Potentiometer and Voltmeter

Academic Session:

2024

Medium:

English Medium

Subject:

Mathematics

Available Material:

Chapter-wise Difference Between Topics


Defining Potentiometer

A potentiometer also referred to as a variable resistor, is an electrical component used to divide voltage in a circuit. It consists of a resistive element, typically a long, uniform wire or a carbon track, with three terminals. The two fixed outer terminals are connected to the ends of the resistive element, while the third terminal is connected to a sliding contact, or wiper, that can be moved along the resistive element. By adjusting the position of the wiper, the output voltage can be varied, providing a variable voltage divider. The properties of potentiometers are:


  • Variable Resistance: Potentiometers allow for the adjustment of resistance in a circuit by changing the position of the sliding contact or wiper along the resistive element.

  • Voltage Division: Potentiometers divide voltage, providing a variable output voltage that is a fraction of the input voltage based on the position of the wiper.

  • Linear or Logarithmic Response: Potentiometers can have linear or logarithmic response curves, determining how the output voltage changes with respect to the position of the wiper.

  • Adjustable Range: Potentiometers have a range of adjustability, allowing for fine-tuning of the output voltage or resistance within specific limits.

  • Mechanical Durability: Potentiometers are built to withstand repeated adjustments and maintain stability and accuracy over time.

  • Mounting Options: Potentiometers come in various mounting configurations, including panel-mounted, PCB-mounted, and through-hole or surface-mount options, making them adaptable to different applications and installation methods.


Defining Voltmeter

A voltmeter is an electrical instrument used for measuring the voltage in a circuit. It typically consists of a calibrated scale, a pointer, and two probes or leads. When connected across a voltage source, the voltmeter measures the potential difference or voltage between the two points. Voltmeters are designed to have a high input impedance to minimize the loading effect on the circuit being measured. They provide accurate and precise voltage readings, often displayed in volts, across a wide range of voltage levels. The properties of voltmeters are: 


  • Voltage Measurement: Voltmeters are designed to accurately measure the voltage or potential difference between two points in a circuit.

  • High Input Impedance: Voltmeters have a high input impedance to minimize the loading effect on the circuit being measured. This ensures that the voltmeter does not significantly affect the voltage being measured.

  • Measurement Range: Voltmeters are available in various ranges to accommodate different voltage levels. They can be designed for specific voltage ranges, such as millivolts (mV), volts (V), or kilovolts (kV), or may have multiple switchable ranges.

  • Accuracy: Voltmeters provide accurate measurements within a specified tolerance. Higher-quality voltmeters tend to have better accuracy.

  • Display: Voltmeters feature a display, commonly digital or analog, to indicate the measured voltage. Digital voltmeters provide precise numeric readings, while analog voltmeters use a scale and a pointer to show the voltage level.

  • Resolution: Voltmeters have a resolution that determines the smallest increment of voltage that can be measured and displayed by the instrument. Higher-resolution voltmeters can detect smaller changes in voltage.


Potentiometer and Voltmeter Differences

S.No

Category 

Potentiometer 

Voltmeter 

1

Purpose

Measures variable resistance or voltage division

Measures voltage or potential difference

2

Output

Provides a variable output voltage

Displays the measured voltage

3

Connection

Connected in series or parallel with the circuit

Connected in parallel with the circuit

4

Reading

Provides a continuous range of values

Provides discrete or specific voltage readings

5

Application

Used for volume control, calibration, and adjustments

Used for measuring voltage in electrical circuits

6

Impedance

Variable depending on the position of the wiper

High input impedance to minimize loading effect


This table provides the main differences between potentiometer and voltmeter. It's important to note that while the terms "alternator" and "generator" are often used interchangeably in common language, in the context of electrical engineering, "generator" typically refers to a device that produces DC or AC, while "alternator" specifically refers to a device that produces AC.


Summary 

A potentiometer and a voltmeter are both electrical instruments used for measuring voltage, but they serve different purposes. Potentiometers are commonly used for applications such as volume control, brightness adjustment, and calibration in electrical and electronic devices. Whereas, voltmeters are essential tools in electrical and electronic applications for monitoring voltage levels, diagnosing circuit issues, and ensuring proper operation of devices and systems.

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FAQs on Difference Between Potentiometer and Voltmeter for JEE Main 2024

1. How does a potentiometer differ from a fixed resistor?

A potentiometer and a fixed resistor differ in their functionality and adjustability. A fixed resistor has a predetermined resistance value that remains constant and unchangeable. It is typically used to provide a specific resistance in a circuit to limit current flow or adjust voltage levels. On the other hand, a potentiometer, also known as a variable resistor, allows for the adjustment of resistance. It consists of a resistive element and a sliding contact (wiper) that can be moved along the resistive element. This adjustability enables the potentiometer to provide variable resistance, making it suitable for applications such as volume control, brightness adjustment, and calibration, where precise control of resistance is required.

2. What is the primary purpose of a potentiometer?

The primary purpose of a potentiometer is to provide variable resistance in an electrical circuit. By adjusting the position of the sliding contact, known as the wiper, along the resistive element, the potentiometer can alter the amount of resistance in the circuit. This adjustability allows for precise control of voltage or current levels. Potentiometers are commonly used in applications such as volume control in audio devices, adjusting brightness in lighting systems, calibration of equipment, and fine-tuning electrical components. 

3. How does a voltmeter measure voltage?

A voltmeter measures voltage by utilizing a sensitive current-measuring device called a galvanometer. When a voltage is applied across the terminals of the voltmeter, a current proportional to the voltage flows through a coil within the instrument. This current creates a torque on a pointer attached to the coil, causing it to deflect on a calibrated scale, indicating the voltage level. To ensure accurate measurements, voltmeters have high input impedance to minimize the current drawn from the circuit being measured. 

4. What are the different types of voltmeters available?

There are several types of voltmeters available, each designed for specific applications and measurement requirements. The main types include analog voltmeters, digital voltmeters (DVMs), and specialized voltmeters. Analog voltmeters use a moving pointer or needle to indicate the voltage level on a scale. Digital voltmeters provide digital readouts and often offer additional features such as auto-ranging and data logging. Specialized voltmeters include true RMS voltmeters for accurate measurement of non-sinusoidal waveforms, high voltage voltmeters for measuring high voltages, and handheld or portable voltmeters for on-the-go measurements. 

5. How can a voltmeter be connected to a circuit for voltage measurement?

A voltmeter can be connected to a circuit for voltage measurement by connecting its two probes or leads across the points where the voltage needs to be measured. The red probe is typically connected to the positive terminal, while the black probe is connected to the negative or ground terminal. The voltmeter should be set to the appropriate voltage range before making the connection. The probes should make secure and direct contact with the circuit without shorting or introducing additional resistance. Once connected, the voltmeter will display the voltage reading, allowing for accurate measurement of the voltage at the desired points in the circuit.