## What is Voltage?

What is voltage?

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. The sources of this force could be chemical reactions inside a battery or the movements of magnetic fields inside a machine. When these happen, the electrons in the metallic elements connected to the source of the force start moving causing a domino effect. The following images illustrate this.

Principle that governs the electron flow concept

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 designated by the letter “E”, or the letter “V”. The unit of measurement for voltage is Volts, which is also 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.

Voltage Circuit Symbol

The terminals of a battery is indicated by a symbol of two opposing perpendicular lines on electrical drawings (schematic diagram). The longer line indicates the positive terminal. The shorter line indicates the negative terminal. The image below illustrates this.

The AC power source is also indicated by the images below.

Units of Measurement

The terminals of a battery is indicated by a symbol of two opposing perpendicular lines on electrical drawings (schematic diagram). The longer line indicates the positive terminal. The shorter line indicates the negative terminal. The image below illustrates this.

The AC power source is also indicated by the images below.

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

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