is the branch of science and technology which makes use of the controlled motion of electrons through different media and vacuum. The ability to control electron flow is usually applied to information handling or device control.
is a basic unit of matter that consists of a dense, central nucleus surrounded by a cloud of negatively charged electrons.
is a subatomic particle carrying a negative electric charge. It has no known components or substructure, and elementary particle. Protons is a subatomic particle with an electric charge of +1 elementary charge. Neutrons is a subatomic particle with no net electric charge and a mass slightly larger than that of a proton.
is a general term for the substance of which all physical objects are made includes atoms and particles which have mass. Matter is commomly said to exist in four states: solid,liquid, gas and plasma.
Sources of voltage:
Types of Current
Direct Current - the flow of electric charge is only in one direction.
- Alternating Current - the movement of electric charge periodically reverses direction.
Pulsating Direct Current - is a direct current that changes in value at regular or irregular intervals.
states that the current through a conductor between two points is directly proportional to the potential difference or voltage across the two points, and inversely proportional to the resistance between them.
The mathematical equation that describes this relationship is:
where V is the potential difference measured across the resistance in units of volts; I is the current through the resistance in units of amperes and R is the resistance of the conductor in units of ohms. More specifically, Ohm's law states that the R in this relation is constant, independent of the current.
is a supply of electrical power. A device or system that supplies electrical or other types of energy to an output load or group of loads is called a power supply unit or PSU. The term is most commonly applied to electrical energy supplies, less often to mechanical ones, and rarely to others.
A power supply may include a power distribution system as well as primary or secondary sources of energy such as:
Conversion of one form of electrical power to another desired form and voltage, typically involving converting AC line voltage to a well-regulated lower-voltage DC for electronic devices. Low voltage, low power DC power supply units are commonly integrated with the devices they supply, such as computers and household electronics.
Chemical fuel cells and other forms of energy storage systems
Generators or alternators