In the field of engineering, those devices which are used for performing measurement of various quantities such as voltage, current, speed, resistance, energy, power, etc., are known as measuring instruments.

These measuring instruments are classified into two main types based on their construction, working and method of showing output −

• Digital Instruments

In this article, we will discuss the key differences between analog and digital instruments that are used for measurement of physical quantities. Also, we will have a short description of analog instrument and digital instrument which will make it easy to understand the differences.

An analog instrument is the one which shows the results of measurement either in the form of a wave or by the deflection of a pointer on an analog scale. Analog instruments work on the principle of electromagnetic induction, where they consist of a magnet (permanent or electromagnet) and a coil through which the current flows. The measurement is then performed by the interaction between the magnetic field of the magnet and magnetic field produced by the electric current in the coil and the results of the measurement are generally shown by the deflection of a pointer on a scale.

The common examples of analog instruments are analog multimeter, analog ammeter and voltmeter, analog speedometer of a vehicle, etc.

## What is a Digital Instrument?

A digital instrument is the type of measuring instrument which represents the output in the form of digits on a screen (LCD or LED). The working principle of a digital instrument is based on the binary number system where, two binary digits (0 and 1) are used to denote two distinct values. The digital instruments are made by solid state devices such as diodes, transistors, MOSFETs, LED, etc. The results shown by the digital instruments are very easy to understand and more accurate. Some common examples of digital instruments are digital multimeter, digital ammeter and voltmeter, digital energy meter, digital speedometer, etc.

## Difference between Analog and Digital Instruments

The following table highlights the major differences between analog and digital instruments −

Basis of Difference
Digital Instrument
Definition
The type of instrument which works on electromagnetic effects and produces the output in analog form (wave or deflection of pointer) is called an analog instrument.The type of instrument which consists of solid state components and shows the results in the digital form (digits on a screen) is known as digital instrument.
Construction
The construction of an analog instrument is simple and direct reading type, involves the use of magnet (permanent or electromagnet) and a coil.The construction of digital instrument is little complex than analog instrument, as it uses electronics and converter circuit for analog to digital conversion and vice-versa.
Output
Analog instruments show the output by the deflection of a pointer on a dial or scale.Digital instrument shows the output on a digital display screen as a text or number.
Environmental conditions
Analog instruments can be used in any type of environmental conditions.Since digital instrument involves electronic devices which requires proper environmental conditions to function.
Moving parts
In analog instruments, moving parts are present.There is no moving parts present in the digital instruments.
Change in output
Analog instruments can show the change in output by the movement of pointer.Digital instruments do not show the change in output quantity.
Error
With the analog instruments, there is a possibility of considerable observational errors like parallax error.Digital instruments are free from observational errors.
Effect of electronic noise
Analog instruments are more susceptible to the electronic noise.Digital instruments are less affected by the electronic noise.
Technology used
Analog instrument uses continuous variation of the signal and records its waveforms.Digital instruments use sampling techniques for the conversion of input signal into binary signal (or digital signal).
Time needed for reading the output
In analog instruments, time required to observe the output is more.Time required for observing the output is very less in case of digital instruments.
Requirement of extra power supply
Analog instruments do not require extra (or auxiliary) power supply.An extra source of power is required in the digital instruments.
Accuracy
Sensitivity
Cost
Size