View source for Basic electricity:1.4 Voltage

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Electricity can be compared with water flowing through a pipe. A force is required to get water to flow through a pipe. This force comes from either a water pump or gravity. Voltage is the force that is applied to a conductor that causes electric current to flow.

[[File:Current_Flow_though_a_Pipe.png|center|Current Through a Conductor|class=img-box]]

Electrons are negative and are attracted by positive charges. They will always be attracted from a source having an excess of electrons, thus having a negative charge, to a source having a deficiency of electrons which has a positive charge. The force required to make electricity flow through a conductor is called a difference in potential, electromotive force (emf), or more simply referred to as voltage. Voltage is desig- nated by the letter "E", or the letter "V". The unit of measurement for voltage is volts which is designated by the letter "V".

== Voltage sources ==
An electrical voltage can be generated in various ways. A battery uses an electrochemical process. A car?s alternator and a power plant generator utilizes a magnetic induction process. All voltage sources share the characteristic of an excess of electrons at one terminal and a shortage at the other terminal. This results in a difference of potential between the two terminals.

[[File:Battery.png|center|Battery|class=img-box]]

== Voltage circuit symbol ==
[[File:Battery_symbol.png|right|Battery symbol|class=img-box]]
The terminals of a battery are indicated symbolically on an electrical drawing by two lines. The longer line indicates the positive terminal. The shorter line indicates the negative terminal.

== Units of measurement for voltage ==

The following chart reflects special prefixes that are used when dealing with very small or large values of voltage:

{| class="wikitable table50"
|+ Unit of Measurement
! Prefix
! Symbol
! Decimal
|-
|1 kilovolt
|1 kV
|1000 V
|-
|1 millivolt 
|1 mV 
|1/1000 V
|-
|1 microvolt 
|1 μA\V 
|1/1,000,000 V
|}