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A | B | C | D
| E | F | G | H
| I | J | K | L | M
N | O | P | Q | R
| S | T | U | V
| W | X | Y | Z
Acceleration: Acceleration is the rate of change
of velocity.
Formula: 
Units: 
or
Alternating current: Current that travels in one direction for
one hundredth of a second but the opposite direction for the next hundredth
of a second.
Amplitude: The amplitude of a wave is the height of the crest
above the average position.
Area: Area is the amount of surface enclosed within the boundary lines.
B
Biomass: This is the chemical energy stored in fast growing plants.C
Centre of gravity: The centre of gravity of an object is the point
through which all the weight appears to act.
Compass: A magnet, which is free to rotate and indicate direction.
Complementary colours: Complementary
colours are two colours which when mixed give white.
See the Colour Triangle
Examples are:
Blue + Yellow
= White
Red + Cyan
= White
Green + Magenta
= White
Concave lens: A concave lens is a lens that spreads out light
rays.
Condensation: This is the changing of a gas to a liquid state.
Conduction: This is the transfer of heat through a solid, without
the movement of the solid.
Convection: This is the transfer of heat through a liquid or a
gas when molecules of the liquid or gas move and carry the heat.
Convex lens: A convex lens is a lens that brings light rays together.
Current: Current is a flow of charge.
Unit: Ampere (A)
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D
Density: Density is the mass per unit volume of the substance.
Formula: 
Units: 
or 
Direct Current: Current that travels in one direction only (i.e.
from the positive terminal to the negative terminal).
Dispersion: This is the splitting up of white light into separate
colours. It can be done by passing white light through a prism.
E
Energy: Energy is the ability to do work.
Equilibrium: An object that is balanced is said to be in equilibrium.
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F
Force, F: A force is that which causes a change in the velocity
of an object.
Unit: Newton, N
Formula: Force = Mass x Acceleration
(F = ma)
Freezing: This is the changing of a liquid to a solid state.
Frequency, f: This is the number of waves that pass a particular
point in one second.
Friction: This is a force which opposes motion between two objects
in contact.
Fuse: A fuse is a safety device in an electric circuit. If the
current gets too high the wire in the fuse melts which breaks the circuit
switching off the current.
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G
Galaxy: A large group of stars held together by its own gravity.
H
Heat: Heat is a form of energy.
Unit: Joules, J
I
Insulator: This is a substance, which does not allow heat to flow
through easily.
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L
Latent heat: This is the heat absorbed or released when a substance
changes state without changing temperature.
Law of conservation of energy: Energy cannot be created or destroyed
but can be converted from one form to another.
Law of the lever: When a lever is balanced the sum of the clockwise
moments is equal to the sum of the anti clockwise moments.
Lever: A lever is a rigid body, which is free to turn about a
fixed point called the fulcrum.
Light: Light is a form of energy.
Loudness: The loudness of a sound depends on the amplitude
Lubricant: A lubricant is a substance capable of reducing friction.
Luminous: A luminous object is an object that gives out light.
Lunar eclipse: This happens when the earth passes between the
sun and the moon.
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M
Magnetic field: A space around a magnet in which the magnetism
can be detected.
Mass, m: The mass of an object is the quantity of matter in it.
Melting: This is the changing of a solid to a liquid state.
Moment: This is a measure of the turning effect of a force.
Formula:
Moment of a force = Force x Perpendicular distance from the fulcrum.
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N
Newton's third law of motion: For every action there is an equal
but opposite reaction.
O
Ohm's law: At constant temperature the voltage across a conductor
is proportional to the current flowing through it.
Formula: Voltage = Current x Resistance
(V = IR)
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P
Pitch: The pitch of a sound is how high or low it is. It depends
on the frequency of the wave.
Potential difference: Potential difference is also called voltage.
It is the force, which moves the electrons around the circuit.
Unit: Volt (V)
Power: This is the rate at which energy is converted from one
form to another.
Unit: Watts (W)
Formula: Power = Voltage x Current
(P = VI)
Pressure: Pressure is force per unit area.
Formula: 
Unit: 
or
Pascal (Pa)
Primary colours: The primary colours are red, green
and blue. When the three of these colours are combined it results in white.
Red + Green + Blue = White
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R
Radiation: This is the transfer of heat by means of invisible
rays, which travel outwards from the hot object, without needing a medium.
Rectifier: This is used to convert alternating current to direct
current.
Reflection: The reflection of light is the bouncing back of light
from a surface.
Refraction: The refraction of light is the bending of light as
it passes from one medium to another.
Resistance, R: The opposition of a conductor to current is called
its resistance. A good conductor has a low resistance and a bad conductor
has a high resistance.
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S
Secondary colours: A secondary colour is formed when
two primary colours are mixed. The three secondary colours are yellow,
magenta and cyan.
Red + Green
= Yellow
Red + Blue
= Magenta
Blue + Green
= Cyan
Solar eclipse: This happens when the moon passes
between the sun and the earth.
Sound: Sound is a form of energy.
Speed, v: Speed is the distance travelled per unit
time.
Formula: 
Unit: m/s
Stable equilibrium: A body is in stable equilibrium
if when slightly moved its centre of gravity rises.
Sublimation: This is the changing of a solid directly
to a gas.
(Iodine is an example of a substance that sublimes).
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T
Temperature: This is a measure of how hot an object is.
Unit: degrees Celsius (
)
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U
Unstable equilibrium: A body is in unstable equilibrium if when
slightly moved its centre of gravity falls.
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V
Velocity: Speed in a given direction.
Units: m/s
Volume: The volume of an object is the amount of space it takes up.
W
Wave: A wave is a means of transferring energy from one point
to another.
Formula: Velocity = Frequency x Wavelength
Wavelength: The wavelength of a wave is the distance between any
two successive crests.
Weight: Weight is the force of gravity on an object.
Formula: Weight = Mass x Acceleration
due to gravity
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