Waves Flashcards
Waves transfer
Energy
In a transverse wave the particles
Vibrate perpendicular to the direction the wave is travelling
In a longitudinal wave the particles
Vibrate parallel to the direction the wave is travelling
/_/_/ this diagram represents a
Transverse wave
|| | this diagram represents a
Longitudinal wave
Examples of transverse waves include
Water, light, radio and television (or any other electromagnetic wave)
An example of a longitudinal wave is
Sound
The frequency of a wave is defined as
The number of waves that pass a point each second
N
f = —
t
The unit of frequency is
Hertz Hz
The speed of a wave is defined as
Distance travelled by a wave in one second
The unit of speed is
Metres per second ms-1
The relationship between speed, distance and time for a wave is
d
v = —
t
The amplitude of a wave is defined as
The size of maximum disturbance from the zero position
The greater the amplitude of a wave
The greater the energy of the wave
The wavelength of a wave is
The distance from one point on a wave to the same point on the next wave
The period of a wave is
The time taken for a wave to pass a point
The unit of wavelength is
Metres m
The unit of period is
Seconds s
The relationship between period and frequency is
1
f = —
T
The relationship between speed, frequency and wavelength is
v = fλ
The relationship between frequency, number of waves and time is
N
f = —
t
Diffraction is the ability of a wave to
Bend round a corner or through a gap
Longer wavelength waves diffract
More than shorter wavelength waves
/\ /\
_/ _/ The line represents the
Amplitude
____
/\ /\ The line represents the
_/ _/
Wavelength
The material a wave passes through is known as
The medium
Electromagnetic waves have a range of
Wavelengths and frequencies
The order of the bands of electromagnetic spectrum, from longest to shortest wavelength is
Radio wave, microwave, infrared, visible light, ultraviolet, x-rays and gamma rays
All electromagnetic waves travel at
The speed of light
Electromagnetic waves are
Transverse waves
A detector of radio waves is
Aerial
Applications of radio waves include
Communication, mri scanners
Detectors of microwaves include
Aerial
Diode detector
Applications of microwaves include
Satellite communication
WiFi
Bluetooth
Radar
GPS
Detectors of infrared include
Photodiode
Blackened thermometer
Thermochromic film
Applications of infrared include
Night vision goggles
Thermographic imaging
Remote controls
Detectors of visible light include
Photodiode
CCD (charged-couple-device)
Photographic film
Applications of visible light include
Photography
Lasers
Detectors of ultraviolet radiation include
Fluorescent chemicals
Photodiode
Applications of ultraviolet radiation include
Fluorescence
Treatment of skin conditions
Sterilisation of medical instruments
Sterilisation of water
A detector of x-rays is
Photographic film
Applications of x-rays include
Radiographs (internal images of objects/people)
Radiotherapy (treatment of cancer)
Detectors of gamma rays include
Geiger-Müller tube
Photographic film
Applications of gamma rays include
Treatment of cancer
Radioactive tracers
Excessive exposure to ultraviolet radiation causes
Skin cancer
Refraction is
The change in speed of light when it passes from one medium into another
When light passes form a fast medium into a slow medium
It’s changed direction towards the normal
When light passes from a slow medium into a fast medium
It changes direction away from the normal
The angle between the normal and incoming ray is called
The angle of incidence
The angle between the normal and out going ray is called
The angle of refraction
In refraction diagrams all angles are measured to
The normal
Sources of microwaves include
Gunn diode
Maser
The sun
Cosmic microwave background radiation
Sources of radio waves include
Aerial
Galaxies
Sources of infrared include
Infrared LED
infrared laser
Sources of visible include
Lamp
LED
Laser
Star
Sources of x-rays include
X-ray tube
Lightning
Supernova remnants
Black holes
Sources of gamma rays include
Radioactive materials
Lightning
Cosmic rays
Neutron stars
Black holes
Sources of ultraviolet radiation include
Ultraviolet LED
ultraviolet lamp
Ultraviolet laser
The sun
What happens to the speed of light as it travels from air into glass?
The speed of light in glass is slower than the speed of light in air.
What path will the ray of light take as it passes through the glass prism?
Light ray is refracted at air/glass boundary and glass/ air boundary. Both result in a change of direction.
As it enters the block the speed of the light decreases and it changes direction towards the normal.
As it leaves the block the speed of the light increases and it changes direction away from the normal.
In the hills you can sometimes pick up a radio signal but not a television signal?
Radio waves are longer wavelengths than television waves.
Radio waves diffract more and can reach the receiver.
What happens when white light is shone through a triangular prism
The light is refracted and produces a spectrum.
Why does a triangular prism produce a spectrum from white light?
Different frequencies/colours of light refract by different amounts.
You are 5km away from a thunder storm. What reaches you first - the thunder or the lighning? Explain your answer.
The lightning. The speed of light is faster than the speed of sound.
Which member of the electromagnetic spectrum has the most energy?
Gamma radiation as it has the highest frequency
