﻿ Quantities and Units of Electricity - Units www.uniteasy.com #### Quantities and Units of Electricity

Electric charge is the quantity to express a matter carries more or fewer elctrons than protons. Positive charge comes from having more protons than electrons; negative charge comes from having more electrons than protons. Like charges repel, unlike charges attract. The SI unit for charge is coulomb (symbol C), or ampere second in terms of SI base unit.

Electric current is a measure of the amount of electrical charge transferred per unit time.It represents the flow rate of electrons through a conductive material. The SI unit of electrical current is the ampere (symbol A), defined as 1 coulomb/second.

Electric resistance is a measure of the degree to which an object opposes an electric current through it. The SI unit of resistance is ohm (symbol Ω). It is defined as the ratio of the voltage applied to the electric current which flows through it.

Electric conductance is defined as the ratio of electric current and electric potential, or the reciprocal of electrical resistance. The SI unit is siemens (symbol S).

Electric potential or electromotive force is the potential energy per unit charge that is associated with a electrostatic field. A special name Voltage (symbol V) is given as its SI unit, which is expressed as watt per ampere in SI derived units.

Capacitance of a capacitor is the ratio of the charge on one of the two plates of the capacitor to the potential difference between the plates. A special name is given as the SI unit of the capacitance - farad (symbol F), which is expressed as coulomb per voltage in terms of SI derived unit.