Y9 Physics Keyword List
Autumn Term – P1 1 Energy transfer by heating
Word
infrared radiation
Definition
Electromagnetic waves between visible light and microwaves in the
electromagnetic spectrum (see P1 6).
emits
gives out
greenhouse effect
trapping of the Sun’s warmth in the atmosphere (air) by chemicals
(e.g. water vapour, carbon dioxide, methane, etc.).
emitters
Objects that give out something.
absorbers
Objects that absorb (take in) something.
reflectors
Objects that reflect waves (allow waves to bounce off of them).
matt
Non-smooth, bumpy surface that does not reflect waves very well.
states of matter
Form that substances take (e.g. solid, liquid and gas).
change of state
When a substance changes from one state of matter to another (e.g.
a solid changing into a liquid).
melting
When a solid changes into a liquid.
solidifying
When a liquid changes into a solid.
freezing
Another word for when a liquid changes into a solid.
evaporation
When a liquid changes into a gas.
boiling
When a liquid changes into a gas at the maximum rate (all of the
energy put into the liquid is used to change the liquid into a gas).
condensation
When a gas changes into a liquid.
sublimation
When a solid changes into a gas when it is heated without becoming
a liquid first.
kinetic theory of
Particle model of solids, liquids and gases which describes their
matter
properties.
density
Mass per unit volume of a substance – can be thought of as how
tightly packed together the particles are in a substance.
conduction
Transfer of heat or an electric current through a substance (usually
solids).
conductor
A substance that allows heat or an electric current to flow through it
easily.
insulator
A substance that does not allow heat or an electric current to flow
through it easily.
free electron
An electron that moves about freely inside a metal and is not held
inside a particular atom.
ion
Charged atom
diffuse / diffusion
Spreading out of particles away from each other.
fluid
Liquid or gas
convection
Transfer of heat through a fluid.
convection currents Circulatory motion in a fluid where a hot fluid rises and cold fluid
moves in to fill its place.
air conditioning unit A system for controlling the temperature of air in a room or vehicle.
energy transfer
Movement of energy from one object to another.
payback time
Time it takes to save back the money spent on something.
U-values
Energy per second that passes through 1 m2 of a material when the
temperature difference between its two surfaces is 1 ˚C.
mass
How much matter (‘stuff’) there is in an object – measured in
kilograms.
specific heat
Energy needed by 1 kg of a substance to increase its temperature by
capacity
1 ˚C.
storage heaters
An electric heater that gains heat in water or bricks over night when
electricity is cheaper and then releases the energy during the day.
Spring Term – P1 5 Waves and P1 6 Electromagnetic Waves
Word
mechanical waves
electromagnetic
waves
sound waves
transverse waves
longitudinal waves
compressions
rarefactions
plane mirror
ray diagram
reflection
image
normal
angle of incidence
angle of reflection
virtual image
Definition
Vibration that travels through a substance.
Electric and magnetic disturbances that transfer energy from one
place to another.
Vibrations that pass through a substance and can be detected as
sound.
Waves in which the vibrations are perpendicular (at 90˚) to the
direction energy is transferred.
Waves in which the vibrations are parallel to (in the same direction
as) the direction energy is transferred.
Parts of a longitudinal wave which are squeezed together, so that
they have a higher density.
Parts of a longitudinal wave which are stretched or spread apart, so
that they have a lower density.
Flat mirror
Diagram drawn to show the direction a wave travels in (usually drawn
for light rays).
When a wave bounces off of the surface of a substance.
A copy of an object formed by a mirror or lens.
Straight line through a surface or boundary perpendicular (at 90˚) to
the surface or boundary.
Angle between the incident ray (approaching a mirror) and the
normal.
Angle between the reflected ray (moving away from a mirror) and the
normal.
An image, seen in a lens or mirror, from which light rays appear to
come from. A virtual image cannot be projected onto a screen and
light rays never meet at its position.
real image
An image formed where light rays meet. A real image can be
projected onto a screen.
refraction
The change in direction of a wave when it passes across a boundary
between two substances (e.g. when light passes from air into glass).
boundary
The surface between one substance and another.
prism
A glass or transparent object, usually triangular in shape, that can be
used to split white light into its different colours.
total internal
When light travelling towards a boundary between a more dense and
reflection
a less dense substance (e.g. glass to air) is completely reflected back
in to the denser substance (e.g. the glass).
diffraction
The spreading of waves when they pass through a gap or around the
edges of an obstacle which has a similar size as the wavelength of the
waves.
crests
Peaks of a transverse wave.
troughs
Bottom most parts of a transverse wave.
amplitude
The height of a wave crest or a wave trough of a transverse wave
from the rest position. In a longitudinal wave, this is the maximum
distance moved by an oscillating object from its equilibrium position.
wavelength
The distance from one wave crest to the next wave crest (along the
waves).
frequency
The number of wave crests passing a fixed point every second.
Hertz (Hz)
Unit of frequency
speed
How fast an object is travelling
white light
Light that is made of all the colours of the visible spectrum.
electromagnetic
List of electromagnetic waves which shows the different types of
spectrum
electromagnetic waves as their wavelength changes.
microwaves
Electromagnetic waves with a wavelength between approximately 1
mm and 10 cm.
radio waves
Electromagnetic waves with a wavelength longer than about 10 cm.
These are electromagnetic waves with the lowest energy.
Bluetooth
Short range radio wave connections which are used to transfer
information.
Satellite
Object in orbit around a planet. Around Earth, some artificial
satellites are used for microwave communications.
visible light
Electromagnetic waves that can be seen by the human eye.
infrared radiation
Electromagnetic waves between visible light and microwaves in the
electromagnetic spectrum.
optical fibre
Thin glass fibre used to send signals.
ultraviolet radiation Electromagnetic waves between visible light and X-rays in the
electromagnetic spectrum.
X-rays
Electromagnetic waves between ultra violet and gamma rays in the
electromagnetic spectrum. They are commonly used for medical
imaging.
gamma radiation
Electromagnetic waves with the shortest wavelengths and the
echo
vacuum
pitch
resonates
Doppler effect
red-shift
blue-shift
galaxy
universe
Big Bang theory
cosmic microwave
background
radiation
Big Yawn
Big Crunch
highest energy in the electromagnetic spectrum.
Reflection of a sound wave – when a sound wave bounces off of a
surface.
An area or space which is entirely empty and contains no matter.
How high a sound wave sounds – it is directly related to its frequency.
When sound vibrations build up in a musical instrument and cause
the sound from the instrument to become much louder.
The change of wavelength (and frequency) of the waves from a
moving source due to the movement of the source towards or away
from the observer.
Increase in the wavelength of electromagnetic waves emitted by a
star or galaxy due to its motion away from us. The faster the speed of
the star or galaxy, the greater the red-shift.
Decrease in the wavelength of electromagnetic waves emitted by a
star or galaxy due to its motion towards us. The faster the speed of
the star or galaxy, the greater the blue-shift.
Collection of billions of stars.
All existing matter and space
The theory that the universe was created in a massive explosion (the
Big Bang) and that the universe has been expanding ever since.
Electromagnetic radiation that has been travelling through space ever
since it was created shortly after the Big Bang. The radiation was
emitted as gamma radiation, but has been red-shifted to microwaves.
The theory that if the density of the universe is less than a certain
amount, it will expand forever.
The theory that if the density of the universe is more than a certain
amount, it will stop expanding and reverse, moving back inwards.
Summer Term – P1 2 Using energy
Word
energy transfer
chemical energy
kinetic energy
gravitational
potential energy
elastic potential
energy
electrical energy
sound energy
light energy
conservation of
energy
pendulum
machine
useful energy
wasted energy
dissipated
weight
newtons (N)
joules (J)
Sankey diagram
input energy
efficiency
Definition
Movement of energy from one object to another.
Energy of an object due to chemical reactions in it. For example
chemical energy is stored in batteries and food.
Energy of a moving object due to its motion.
Energy of an object due to its position in a gravitational field.
Energy stored in an elastic object when work is done to change its
shape. E.g. energy stored in a stretch elastic band.
Energy transferred by the movement of electrical energy.
Energy transferred by sound waves.
Energy transferred by visible waves.
Law that energy cannot be created or destroyed.
A mass attached to the end of a rod or string. When moved from
their still position they swing from side to side, and are used in some
clocks.
Device or object used to do something useful.
Energy transferred to where it is wanted in the form it is wanted.
Energy that is not usefully transferred.
Energy is spread out to the surroundings, usually in the form of heat.
The force of gravity on an object.
The unit of weight.
The unit of energy.
A diagram to show how energy is transferred in a particular situation
Energy put into a system or device.
Useful energy transferred by a device divided by the total energy
supplied to the device. It is a measure of how good a device is at
transferring energy usefully.