555 Time
A type of integrated circuit. The chip is used comenly in timer circuits.

AC
Alternating current, current that continuously varies in a sinusoidal manner. The polarity goes from - to + 50 times per second in the UK and 60 in the USA. We say this is 50/60Hz. AC is used to supply electricity to buildings. AC opposes DC.

Analogue
US:Analog. A continuously changing number. In electronics, analogue opposes 'digital'.

AND
A type of logic function where the output is high (logic 1) only when all inputs are high.

Angular Velocity
The rate of rotation around an axis (in radians). Known as rotation rate. Measured in degrees per second.

Armature
The moving part of an electromagnetic device. The part that spins in a motor, generator or alternator.

Axle
A rod that is free to rotate. for example, the part a wheel is attached to.

Binary
A way to count using two characters - 0 and 1. Used in digital circuits.

Chamfer
A sloping edge caused by cutting away the corner of a shape. A beveled edge. Used to remove any sharp or uneven edges.

Commutator
The part of a motor that is attached to the armature and directs current into the windings of the motor. It is the rotating part of a DC generator.

Component
The name given to an electronic part. For example, resistor and capacitor. 

Contact
The electromotive force or electric potential that causes a current to flow in a circuit. Switches are two contacts, when separated they break a circuit and when connected, make a circuit.

Current
The flow of electric charge through a conducting material. Measured in amperes. The current is like the speed of water coming out of a hose pipe.

Demagnetise
To lose magnetism.

Denary
A number system that uses 10 numbers. This is the most common way of counting. numbers range from 0-9. See also, Binaryand hexadecimal.

Diameter
The length of a straight line that passes from one edge of a circle to the opposite edge. The diameter symbol is 'd'.

Digital
A value that is either, 1 or 0, on or off, open or closed etc. Digital opposes analogue. Digital signals are used in microprocessors to tell them which pins to allow current to flow. So, 1 would mean open and 0 would be close.

Diode
A component that will only allow current to pass through it in one direction. This accounts for many components, one being the LED (Light Emitting Diode).

Electrodes
A solid conductor that is used to make electrical contact with a non-metallic material. Can provide the chemical action needed to turn chemical energy into electrical energy. This process is used in batteries.

Electromagnet
A temporary magnet consisting of a soft iron core wrapped with a wire coil that becomes magnetic when current is passed through the coil. With a switch, it is a magnet on demand. Used to lift heavy metal easily.

Electromagnetic coil
A coil of wire that creates a magnetic field when current is passed through it.

Electron
A particle inside an atom that has a negative a charge. Electrons that search for an atom needing them is the flow of electricity 

Energy (Electrical)
The energy made available by the flow of electrical charge through a conductor. It is measured in kilowatt-hours (kWh), megawatt-hours (NM) or gigawatt-hours (GWh).

Hexadecimal
A form of counting using 16 characters. Characters from 0-9 are in denary, the other 6 are from A-F. So, 0123456789ABCDEF.

Instantaneous
At any instant in time. 'At an instant'.

Lead
A wire that connects to a component. Used when the connecting components aren't on the same printed circuit board.

Light Emitting Diode (LED)
A component that produces light. This only lets current flow through it one way. The short leg is negative and the long leg is positive. The flat side of the LED indicated the cathode (negative).

Linear motion
Movement in a straight line, backwards and forwards.

Magnet
An object that is surrounded by a magnetic field that will attract iron or steel to it.

Magnetises
To become magnetic.

Milliamp (mA)
A unit of measurement for current, equal to 0.001 of an amp.

Minimisation
The process used to simplify a logic circuit. The PCB track is moved closer to it's neighbor to make the board smaller and to save space. Programs are used to do this.

Minimising
The process of simplifying a logic circuit.

NAND
A type of logic function where the output is low (logic 0) only when all inputs are high (logic 1).

NOR
A type of logic function where the output is low (logic 0) when any of the inputs are high (logic 1).

NOT
A type of logic function where the output logic level is opposite to the input logic level.

OR
A type of logic function where the output is high (logic 1) when any of the inputs are high.

Ohm's Law
The law that defines the relationship between current, voltage and resistance. To find volts, cover the 'V', to find current, cover the 'I', to find resistance, cover the 'R'.

Oscillating
Voltage or current that moves between two extremes back and forth at a constant rate.

Oscillator
A device that produces electrical oscillation.

PIC Microcontroller
Stands for Programmable Interrupt Controller. Programmable chip used in modern day electronics.

Pin
Electrical connection point on a component.

Pin-out
microhenry, a unit of measurement for inductance, equal to 0.000001 of a henry.

Polarised
The amount of electrical energy in a circuit. Measured in watts . Watts = amps x volts.

Resistor
A component that limits the flow of charge (current) in a circuit. Protects other components from receiving too much current and burning out.

Power
The amount of electrical energy in a circuit. Measured in watts . Watts = amps x volts.

Resistance
The property that limits the flow of charge (current) in a circuit.

Rotational motion
Movement in a circular manner by rotating or spinning. For example, a motor.

Sinusoidal
A waveform of the sine function. Also know as the sine wave.

Tolerance
How much above and below a value a load can be. When talking about resistors, a tolerance of 1% (brown colour band) on a 100 ohm resistor would tell you the resistor could vary from 99 ohms and 101 ohms. The tolerance will tell you the quality/ accuracy of a resistor, a lower tolerance rating will be more accurate.

Truth table
A table used with logic circuits that shows the output logic level for every combination of input levels.

Voltage
The measurement of a unit of voltage.

Watt
The measurement of a unit of power.

XNOR
A type of logic function where the output is off when the two inputs are different.

XOR
The opposite of the XNOR logic function. When both inputs are different, the output it on.