Unit of Current

What is Electric Current?

We hear a lot about electric currents in our daily life: in the classroom as well as at our home. The electric current in terms of scientific understanding is basically the flow of current or charge in electric circuits. The charge is sometimes simultaneously carried by the ions and electrons. 

The charge of the current flowing through the circuit needs to be measured. It enables us to understand the performance of the circuit and the circuit to operate as required. Electric current is measured by an ammeter and its unit is Ampere or Amp. However, nowadays there are different measurement methods for taking the unit of current.


SI Unit of Electric Current?

The SI unit of Electric current is symbolized by Ampere, which measures the movement of the electric charge through a surface at a rate of one coulomb per second. As the charge is measured in coulombs, and time in seconds; so the unit becomes coulomb/sec (C/s) or amp. The formula for measuring the electric current is given below.

I = V/R 


  • I = Electric Current

  • V = Voltage

  • R = Resistance of the material

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One of the SI basic units for electric current is Ampere, which is mostly used in the electronic and electrical science as well as other areas of science. Based on the electromagnetic effect, induced Ampere can be defined. 


What is the Unit of Current?

To define the unit of current, the Ampere is nominated after Andre-Marie Ampere, who was one of the early forerunners in electrical science. However, the practical realization of the Ampere is equivalent to a charge of coulomb per second flowing in a circuit. The formal description of an ampere is the constant current which if continuous in two straight parallel conductors of infinite length, of insignificant circular cross-section, and placed one meter apart in vacuum, would yield between these conductors a force equal to 2 × 10⁻⁷ newton per meter of length


Conditions for the Definition of the Ampere     

The symbol I was decided to symbolize the intensity of a current by the 19th-century French physicist and mathematician Andre-Marie Ampere.

The SI unit of electric current is known as Ampere, and it is one of the seven SI base units.

Interestingly, one ampere is roughly equivalent to approx 6.24×10¹⁸ elementary charges such as holes or electrons going past a given point or limit in one second. Physicists consider current to flow from moderately positive points to somewhat negative points; this is called standard current or Franklin current.

This definition uses electromagnetism to define the unit of current. This starts to implicitly verify the value for the magnetic constant µ0 = 4 π 10⁻⁷ Hm-1 = 4 π 10⁻⁷ m kg s² A⁻². Therefore, the base unit ampere and thus, all other electrical units is associated with the base unit’s meter, kilogram, and second via this important constant.

In written languages, without accentuated letters (namely English), it has become normal to write the unit as Ampere and, in confidential communication, to reduce the word to an amp. There is no need to use capital “A” at the starting Ampere as implied to physicists. Here, Ampere (or amp) suggests a unit.

This is an algebraic link, not a definition. An Ampere is a vital unit in the International System while other units are obtained from it. Here, the fundamental units identify this research. In the case of the Ampere, the testing is electromagnetic in nature.


Some Standard Electrical Units of Measure

Separately from Ampere, there are many standard units of measurement used for the articulation of electrical properties like the voltage, power, capacitance, resistance, inductance, electric field, electric charge, frequency, the magnetic flux which are all linked to electric current.

Electrical Parameter

Measuring Unit




V or E



R or Ω









L or H












G or ℧


How to Measure the Unit of Current?

Ampere meter, normally known as Ammeter, is an electrical device used to measure electrical current in Amperes. The electrical current on the load is quantified with the help of an Ampere meter by linking it in series to the load. It has zero resistance, and so the calculated circuit remains unchanged.

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The Ammeter cannot be linked in parallel to the load because of its minimal resistance. If it is linked in parallel, it becomes a short circuit path granting all the current to flow through it, which may be steered to the burning of the meter due to the elevated value of current. An ultimate ammeter has zero impedance so that the power failure in the instrument is zero. But this ideal situation is not practically achievable.


Types of Ammeter

The categorization of the Ammeter is based on the building design and the type of current that flows through it.


 Based on the Layout of the Structure, it is Categorized as Follows:

  • Moving iron ammeter

  • Rectifier type ammeter

  • Permanent moving coil ammeter

  • Electro-dynamometer ammeter


Based on the Kind of Current that Flows through it, it is Categorized as Follows:

  • DC ammeter

  • AC ammeter

The DC ammeters are mostly constant moving coil type ammeters. The other types of Ammeter can quantify both AC and DC current.

FAQ (Frequently Asked Questions)

1. List a Divergence Between Volt and Ampere.

Ans: Voltage is calculated in volts, the current is quantified in amps

2. How Much is One Amp?

Ans: A current of 1 A is comparable to transferring 6.24 × 1018 charge carriers through a particular point in a second.

3. How Many Electrons are in One Ampere?

Ans: One ampere symbolizes a movement of one coulomb of electrical charge per second. It gets 6.25 x 1018 electrons to get up 1 coulomb of charge.

4. Who is Ampere, and What Did he Do?

Ans: Andre-Marie Ampere was a French physicist who founded and identified the science of electrodynamics. It is also known as electromagnetism.