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electricity keywords

Terms in this set (40)

alternating current, a.c.
Electrical current that repeatedly reverses its direction, like mains electricity
ammeter
Instrument that measures electrical current in amperes. Connected in series
ampere, amp, A
Unit of current. The charge that flows during one second
charge, Q
Fundamental property of matter that produces all electrical effects
conventional current
Movement of positive charge that is imagined to move from the positive terminal to the negative terminal of a battery. Equivalent in effect to the real flow of negative charge (electrons) in the opposite direction.
coulomb, C
Unit of electric charge
diode
Device that only lets electricity flow through it one way
direct current, d.c.
Current that always flows in the same direction
current, I
Flow of electric charge. Measured in Amps. The number of coulombs of charge that flow per second.
electron
Negatively charged particles with a negligible mass that form the outer portion of all atoms. Flow in a circuit to make a current.
fuse
A component made of a thin wire that protects a circuit from electrical fire. If the current gets too large, the fuse wire melts (the fuse 'blows') and stops the current.
Ohm's law
The current flowing through a component is proportional to the potential difference between its ends, providing temperature is constant.
parallel
Describes a circuit in which the current splits up into more than one path.
potential difference, p.d.
The energy transferred from one coulomb of charge between two points. Measured in volts. Often called the 'voltage'.
power, P
Amount of energy transferred every second. The energy can be transferred from somewhere (e.g. a power station) or to somewhere (e.g. an electric kettle). P = V x I
resistance, R
Property of an electrical conductor that limits how easily an electric current flows through it. Measured in ohms.
series
Describes a circuit in which the current travels along one path through every component.
short circuit
Unwanted branch of an electrical circuit that bypasses other parts of the circuit and causes a large current to flow.
variable resistor
Component with a resistance that can be manually changed.
volt, V
Unit of voltage. Energy carried by one coulomb of electric charge.
watt, W
Unit of power. One watt is one joule transferred every second.
switch
A component in a circuit. When closed the current can flow. When open the current cannot flow.
L.D.R.
Light Dependent Resistor. Light = low resistance; dark = high resistance
lamp / bulb
Component which changes electrical energy into light energy
insulator
A material which does not allow electric current to flow through it (it has high resistance)
voltmeter
A device which is used to measure the voltage across a component; connected in parallel
L.E.D.
Light Emitting Diode. A component which gives out light when current flows the right way through it.
voltage, V
The potential difference across a component in a circuit. Measured in volts
appliance
An electrical device with a specific function; cooker, washing machine, T.V.
kilowatt hour, kWh
Unit of energy normally used to measure the amount of electricity. Energy (kWh) = Power (kW) x time (h)
filament
A very thin piece of tungsten wire inside a lamp. Gets very hot when a current passes through it and glows white hot
ohm, Ω
Unit of resistance.
resistor
A component which limits the flow of a current by converting electrical energy into heat energy.
thermistor
A resistor that's resistance depends on temperature. Hot = low resistance; cold = high resistance
conductor
A material which allows electrical current to flow through it (it has low resistance)
battery
More than one cell.
R.C.D.
Residual Current Device. A device which switches off a circuit if the current in the live wire is different to the current in the neutral wire. Can protect against electrical shock
cell
A component which changes chemical potential energy to electrical energy. Makes d.c.
mains
The domestic electricity supply. In Thailand it is 220V, 50Hz, a.c.
double insulation
When an appliance has a casing that is an insulator (usually plastic).
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