Electric current

What Is the Electric Current Intensity? Amperage Definition and Formula

What is the electric current intensity? Amperage definition and formula

The current intensity is the electrical charge that passes through a section of the conductor per second.

An electric current in a wire, where the charge carriers are electrons negatively charged, is a measure of the quantity of charge passing any point of the wire per unit of time.

A flow of positive charges (such as protons or positive ions) has the same effect in a circuit, as an equal flow of electrons in the opposite direction.

The following formula gives the amperage:

I = Q / t


  • “I” represents the electric current intensity expressed in Amps (A).

  • “Q” represents the electric charge expressed in Coulombs (C).

  • “t” represents the time which is expressed in second units (s).

With this definition, we can say that an electric current has an intensity of 1 amp when a load of 1 colombium passes through a section of the conductor in 1 second.

What Is the Unit to Measure the Intensity of an Electric Current?

The unit of measurement for intensity is Ampere A in the International System of Units.

The ampere unit is named after André-Marie Ampère.

The intensity of an electric current is measured with the galvanometer. For a correct measurement, the galvanometer must be placed in series with the electrical conductor whose amperage is to be measured.

What is the electric current intensity? Amperage definition and formula An ammeter is a galvanometer calibrated in amps.

What Are the Amp-hours Units?

An ampere-hour is a unit that measures the amount of electrical charge that flows through a storage device if it supplies a current of 1 ampere for 1 hour. An ampere-hour equals 3,600 coulombs.

How Is the Current Intensity Generated?

Imagine two ends of the same conductor. Each lot is subjected to a different electric field with different electric potentials.

Due to this potential difference, the electrons present in the conductor experience attractive and repulsive forces. These electrical forces cause the free electrons to move.

The electrical charges move at a certain speed. We consider any section located at a point between the two extremes. A certain number of electrons per second will pass through this section, which is the same: a certain amount of electricity per second.

That amount of electric power per second is called the intensity of the electric current expressed in amps.

Two types of electric current can exist in an electrical circuit :

  • Direct current (DC) is the current where electrical energy always flows in the same direction.

  • Alternating current (AC) is the form of current where the charges change its sense periodically.

What Is the Current Density?

With the current density, we can express the average quantity of electricity per unit of a conductor's bone. The current density is designated by the symbol J. In the definition of current density, we assume that current flows uniformly through the conductor cross-section.


J is measured in the International System units in A / m 2 (amps per square meter). However, given the conductors' dimensions, it is common to express it in A / mm2. As it is the conductor section, it is more manageable to measure in square millimeters.


Published: November 17, 2019
Last review: October 25, 2020