Waves Flashcards
What is a transverse wave?
When the vibrations are perpendicular (90) to the direction of energy transfer of the wave
What is a longitudinal wave?
When the vibrations are parallel to the direction of energy transfer of the wave
What is the electromagnetic spectrum?
Radio waves Micro waves Infrared Visible light Ultra violet X Ray Gamma rays
What is the order of the electromagnetic spectrum based on?
Increasing frequency and energy
Decreasing wavelength
EMs with a higher frequency have a shorter wavelength
What is the wavelength of the EM spectrum between?
10 to the power -16 metres and 10 to the power 4 metres
What is the speed of the EM waves I’m a vacuum
3x10 to the power 8m/s
What are the used of radio waves?
Communicating
Broadcasts
Radar
What are the uses of microwaves?
Satellite communication
Cooking
What are the uses of infrared?
Cooking
Remotes
Thermal imaging
Optical fibres
What are the uses of visible light?
Optical fibres
Endoscopes
What are the uses of ultraviolet?
Security markings
Identifying forged bank notes
Fluorescent tubing
What are the uses of X-Ray’s?
Medical imaging
Airport security
What are the uses of gamma rays?
Radio therapy
Sterilise medical equipment
What are the dangers of radio waves?
None
What are the dangers of microwaves?
Heating water in tissues=burning
What are the dangers of infrared?
Causes burning in human tissue
What are the dangers of visible light?
Activates sensitive cells in the retina
What are the dangers of ultra violet?
High=kills cells
Low=causes cancer
What are the dangers of X rays?
High=kills cells
Low=causes cancer
What are the dangers of gamma rays?
High=kills cells
Low=causes cancer
What is a virtual image?
An image that cannot be projected such as the one in a mirror
What is frequency
The number of waves per second
What are the rules about a virtual image?
The image is the same size as the object
The image is the same distance away
The image is upright
It is laterally inverted
What type of waves are sound waves?
Longitudinal
What are echoes?
Echoes are reflected waves of sound
When are sound waves reflected?
When they meet hard flat surfaces
When are sound waves refracted?
When they enter denser material they speed up
What is high and low frequency?
Low frequency=low pitch and short wavelength
High frequency=high pitch and long wavelength
What determines the loudness of the sound?
The amplitude of the sound wave, the bigger the amplitude the louder the sound
How to know amplitude?
The distance between the centre line and top of crest
How to know wavelength?
The distance between any point on one wave to the same point on the next wave along
What are examples of longitudinal waves?
Sound waves and ultrasound waves
Shock waves e.g. Seismic waves
A slinky spring when you push the end
What are examples of transverse waves?
Light and all other EM waves
Ripples on water
Waves on strings
A slinky wiggled up and down
What does loudness depend on?
Amplitude
The bigger the amplitude the louder the sound
How can long radio waves be transmitted over a large distance?
1-10km
The long wavelength diffracts around the curves earths surface meaning signals can be received even if the receiver isn’t in line with the transmitter
How can short wave radio signals be transmitted over long distances? 10m-100m
They’re reflected from the ionosphere (an electrically charged layer in the earths upper atmosphere)
Médium eave signals can also do this depending on atmospheric conditions and the time of day
How do micro waves work?
Signal from a transmitter is transmitted into space
It is picked up by a satellite receiver dish orbiting the earth
The satellite transmits the signal back to earth in a different direction where it’s received by a satellite dish on the ground
Where does sound travel faster and where can’t it travel?
Faster in solids
Can’t travel In a vacuum
What is frequency in sound?
The number of complete vibrations per second
How is visible light used for photography?
Cameras use a lens to Focus visible light onto the light sensitive film
