Difference Between Potentiometer and Voltmeter

A potentiometer and a voltmeter are two different electrical instruments used in circuit analysis. The difference between a potentiometer and a voltmeter can be defined with respect to many aspects such as construction, working principle, types, applications etc..

Definition:

A potentiometer, also known as a variable resistor or pot, is a three-terminal device primarily used to measure and control electrical resistance. 

A voltmeter is a measuring instrument used to measure electrical potential difference or voltage between two points in a circuit. It is connected in parallel across the component or circuit whose voltage is to be measured.

Construction:

A potentiometer consists of a resistive element, typically a long, uniform wire or a carbon composition track, with three terminals: a fixed terminal at one end, a variable terminal (wiper) that moves along the resistive element, and another fixed terminal at the opposite end.

Voltmeters can be analog or digital. Analog voltmeters usually consist of a moving coil mechanism, where a current-carrying coil deflects a pointer on a calibrated scale. Digital voltmeters, on the other hand, use electronic circuits to measure and display the voltage.

Working Principle:

As the wiper position is adjusted along the resistive element, the effective resistance between the wiper and the fixed terminals changes. This variation in resistance allows the potentiometer to control voltage or current in a circuit.

Voltmeters are connected in parallel to the circuit or component being measured. They have high input impedance (resistance) to minimize the current drawn from the circuit, ensuring accurate voltage measurement without significantly affecting the circuit's behavior.

Types:

Potentiometers can be categorized into two main types: linear potentiometers and logarithmic (audio taper) potentiometers. Linear potentiometers have a linear relationship between the wiper position and resistance, while logarithmic potentiometers have a logarithmic taper, which corresponds to the human ear's response to sound.

Voltmeters can be categorized into two main types: analog voltmeters and digital voltmeters. Analog voltmeters provide a continuous scale reading using a moving pointer, while digital voltmeters display the measured voltage in numerical form on a digital screen.

Applications:

Potentiometers have a wide range of applications, including audio equipment (such as volume controls and tone controls), calibration of instruments, level adjustment in amplifiers, voltage division, position sensing, and temperature control.

Voltmeters are used in a wide range of applications, including electrical maintenance and troubleshooting, laboratory experiments, electronics prototyping, power system analysis, automotive diagnostics, and industrial control systems.

In summary, while both potentiometers and voltmeters are electrical instruments, the primary difference between potentiometer and voltmeter is that the former is used to vary resistance or control voltage levels, while the latter is specifically designed for measuring voltage differences in circuits.