Unit

Definition(s)

Coulomb (C)

- the SI unit for electric charge

- the amount of electric charge move by one ampere of current per second, i.e., 1 C = 1 A-second

- the amount of charge stored by 1 farad of capacitance with 1 volt across it, i.e., 1 C = 1 F x 1 V

Ampere (A)

- the SI unit for electric current

- the amount of current flowing in two parallel conductors of infinite length one meter apart in vacuum that would produce a force betwen these conductors equal to 2e-7 newtons per meter of length

-  the amount of current that flows through a 1-ohm resistor with 1 volt across it, i.e., 1 A = 1 V / 1Ω

-  the amount of current that moves 1 coulomb of charge per second

Volt (V)

- the SI unit for voltage

- the potential difference between two points in a conductor when a current of 1 ampere flowing through the conductor dissipates 1 watt of power between these two points

- the voltage across 1 ohm of resistance when a current of 1 ampere is flowing through it, i.e., 1 V = 1 A x 1  Ω

Ohm (Ω)

- the SI unit for electrical resistance

- the amount of resistance that produces one volt across it when 1 ampere of current is flowing through it, i.e., 1 Ω = 1 V / 1 A

Farad (F)

- the SI unit for capacitance

- the amount of capacitance that produces a potential difference of 1 volt across it if it stores 1 coulomb of charge, i.e., 1 F = 1 C / 1 V

Henry (H)

- the SI unit for inductance

- the amount of inductance that produces an electromotive force equal to 1 volt when the rate of change of current through it is 1 ampere per second

Siemens (S)

- the SI unit for electrical conductance G = 1 / R = I / V; where R, I and V are the resistance of, current through, and the voltage across the conductor, respectively

- formerly known as the 'mho', the obsolete term for conductance

- the amount of conductance that allows 1 ampere of current to flow through a conductor when 1 volt is applied across it, i.e.,

1 S = 1 A / 1V

Weber (Wb)

- the SI unit for magnetic flux

- the amount of magnetic flux change per second through a loop that will produce an electromotive force of 1 volt, i.e.,

1 Wb = 1 volt-second

Joule

- the SI unit for work

- the amount of work done by a force equal to 1 newton acting over a distance of 1 meter

Watt

- the SI unit for power

- the amount of power that produces 1 joule of energy per second

- the amount of power dissipated by a 1-ohm resistor when it has 1 volt across it or 1 ampere through it

Watt-hour

- the amount of energy consumed when 1 watt of power is expended for 1 hour of time