# Electric current | Definition | Types | Formula | Unit

Contents

## What is Electric Current

Electric current is defined as the rate of change of charge passing through a specified area. The electric current is denoted by “i”. The current in a circuit or wire can be measure by measuring the quantity of charge “q” passing through a cross section of a circuit or wire in a time “t” . The current is simply the ratio of the quantity of charge and time.

Current is a rate quantity, this can be expressed mathematically as \\\;\\\;\;\;\;i=\frac{dq}{dt}\\\;\\ where “q” is a net charge and “t” is the time.\\\frac{dq}{dt} is rate of change of charge.\\“i” stands for instantaneous current.

## Unit of Electric Current

Electric current is measured by SI Unit called Ampere. It is denoted by “A”.\\\;\\ Current,\;\;i=\frac{q}{t}\\\;\\ The unit of charge (q) is coulomb (c) and unit of time (t) is second (sec). \\\;\\Thus \;\;i=\frac{coulomb}{second}= Ampere

One ampere of current is defined as when one coulomb (6.241 x1018 electrons) of charge is moving through a cross section area in one second.

## Types of Electric Current

There are two types of electric current – Direct current (DC) and Alternating Current (AC).

Direct Current:- The direct current does not change its magnitude and direction with time. The frequency of DC is zero. The batteries and solar cells produce direct current.

Alternating Current:- The alternating Current changes its magnitude and direction with respect to time. It has frequency. The frequency of AC in India is 50Hz while some European countries have 60Hz.

Alternating Current can be converted into Direct current by rectifier while Direct current can be converted into Alternating Current by inverter.