P5 Waves in Matter Definitions:
Amplitude- the maximum displacement of a wave from its undisturbed (equilibrium)
position.
Colour- the colour of an object is determined by which wavelengths of light reflect from it.
All other wavelengths are absorbed.
Concave lens- a lens that is thicker at the edges than in the centre. Parallel rays diverge
when passing through.
Convex lens- a lens that is thicker in the centre than at the edges. Parallel rays converge
when passing through.
Diffuse reflection- the reflection of a wave from a rough surface that results in the wave
being scattered.
Electromagnetic spectrum- a group of transverse waves that cover a large range of
frequencies and wavelengths. The highest frequency waves in the spectrum are gamma-rays
and the lowest are radio waves.
Electromagnetic waves- transverse waves that transfer energy from the source of the
waves, to an absorber. They form a continuous spectrum of different frequencies and all
travel at the same speed in a vacuum.
Focal length- the distance between the centre of a lens and its principal focus.
Foetal scanning- a method of producing an image of a foetus in a womb through the
emission, reflection and detection of ultrasound waves.
Frequency- the number of waves passing a given point in a second. It is the inverse of the
wave’s time period.
Gamma rays- high energy radiation rays used for detecting and treating cancers, and
sterilising food and medical implements. They can cause cell damage and mutations.
Hertz (Hz)- the unit of frequency.
Infrared radiation- a type of radiation that all objects emit and absorb. The hotter an object
is, the greater the infrared radiation it emits in a given time.
Infrared- used for cooking food, thermal imaging and short range communications. It can
cause skin burns.
Law of reflection- the angle of incidence must always equal the angle of reflection when a
wave reflects.
Lens- an object that forms an image through the refraction of light.
Longitudinal waves- waves with oscillations that are parallel to the direction of
travel/energy transfer.
Microwaves- used for satellite communications and for cooking food. They can cause
internal heating of body cells.
Principal focus- the point before or after a lens where light rays appear to meet.
Radio waves- used for television and radio signals. They can be produced by
oscillations in electrical circuits, or can induce these oscillations themselves.
Real image- an image produced by light-rays physically converging. Real images are ones
that can be projected onto a screen.
Reflection- the bouncing back of a wave at a boundary.
Refraction- the changing of speed, and consequently the direction, of a wave as it changes
medium. The wavelength of the wave will also change but the frequency remains constant.
Seismic waves- waves that are produced by earthquakes.
Specular reflection- the reflection of a wave from a smooth surface.
Amplitude- the maximum displacement of a wave from its undisturbed (equilibrium)
position.
Colour- the colour of an object is determined by which wavelengths of light reflect from it.
All other wavelengths are absorbed.
Concave lens- a lens that is thicker at the edges than in the centre. Parallel rays diverge
when passing through.
Convex lens- a lens that is thicker in the centre than at the edges. Parallel rays converge
when passing through.
Diffuse reflection- the reflection of a wave from a rough surface that results in the wave
being scattered.
Electromagnetic spectrum- a group of transverse waves that cover a large range of
frequencies and wavelengths. The highest frequency waves in the spectrum are gamma-rays
and the lowest are radio waves.
Electromagnetic waves- transverse waves that transfer energy from the source of the
waves, to an absorber. They form a continuous spectrum of different frequencies and all
travel at the same speed in a vacuum.
Focal length- the distance between the centre of a lens and its principal focus.
Foetal scanning- a method of producing an image of a foetus in a womb through the
emission, reflection and detection of ultrasound waves.
Frequency- the number of waves passing a given point in a second. It is the inverse of the
wave’s time period.
Gamma rays- high energy radiation rays used for detecting and treating cancers, and
sterilising food and medical implements. They can cause cell damage and mutations.
Hertz (Hz)- the unit of frequency.
Infrared radiation- a type of radiation that all objects emit and absorb. The hotter an object
is, the greater the infrared radiation it emits in a given time.
Infrared- used for cooking food, thermal imaging and short range communications. It can
cause skin burns.
Law of reflection- the angle of incidence must always equal the angle of reflection when a
wave reflects.
Lens- an object that forms an image through the refraction of light.
Longitudinal waves- waves with oscillations that are parallel to the direction of
travel/energy transfer.
Microwaves- used for satellite communications and for cooking food. They can cause
internal heating of body cells.
Principal focus- the point before or after a lens where light rays appear to meet.
Radio waves- used for television and radio signals. They can be produced by
oscillations in electrical circuits, or can induce these oscillations themselves.
Real image- an image produced by light-rays physically converging. Real images are ones
that can be projected onto a screen.
Reflection- the bouncing back of a wave at a boundary.
Refraction- the changing of speed, and consequently the direction, of a wave as it changes
medium. The wavelength of the wave will also change but the frequency remains constant.
Seismic waves- waves that are produced by earthquakes.
Specular reflection- the reflection of a wave from a smooth surface.
