# Electronics – Electrical Unit Definitions

Definitions of basic measurement units in electricity and electronics

## Ampere (A)

Unit of measurement of electric current. Is the amount of charge that flows through a conductor in a unit of time. I = Q/t

Ampere is the electric current (I) that produces a force of 2 x 10-7newton per meter between two parallel conductors separated by 1 meter. 1 A = 1 coulomb / second. 1 A = 1000 mA (milliampere). See also: ## Coulomb (C)

Coulomb is the measuring unit of the electric charge. Q load passing through a point in one second when the current is 1 ampere. 1 Coulomb = 6.28×1018 electrons.
See: Coulomb’s Law

## Joule (J)

Joule is the work (W) made by the force of one Newton acting over the distance of 1 meter.

## Watt (W)

Watt is the power unit. Power (P) required to perform a work at a rate of 1 joule per second.
See: Joule’s Law

## Henry (H)

Henry is the inductance measurement unit. Henry is the inductance (L) where 1 volt is induced by a change of 1 ampere per second. See also:

## Ohm (Ω)

Unit of measurement of the electrical resistance, represented by the capital Greek letter (Ω) omega. Ohm is the resistance that produces a voltage of 1 volt when it is traversed by a current of 1 ampere. See also:

• Electrical resistance
• Variable resistor (potentiometer, rheostat)
• Wirewound resistor
• Resistors color coding
• Measuring ranges for resistors on a VOM
• Measure resistance of low value
• Measure sensitive resistors

## Siemens (S)

Siemens is the unit of measure of the conductance (G). Siemens is the conductance which produces a current of 1 ampere when a voltage of 1 volt is applied. It is the reciprocal of the ohm, formerly called mho.

## Volt (V)

Volt is the unit measuring the electrical potential difference or voltage. Voltage is the potential difference between two points in a conductor carrying a current of 1 ampere when the power dissipated between the two points is 1 watt.

## Hertz (Hz)

Hertz is the number of complete cycles of a wave in a unit of time. 1 Hertz = 1 cycle/sec. See also: Alternating Current (AC)

Radian is the angle which covers the circumference portion which is equal to the length of the radius of the circle.

## Angular frequency (w)

π = 3.14159265359….

## Time (t)

Time measurement unit (Sec) See: Time constant.

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