EM Waves and their Uses Flashcards
What are microwaves used for? Why?
Communication to and from satellites. They can pass easily through earth’s watery atmosphere unlike radio wave
How does satellite TV work?
The signal from a transmitter is transmitted into space where it’s picked up by the satellite’s receiver dish orbiting thousands of kilometres above Earth. The satellite transmits the signal back to Earth in a different direction where it’s received by a satellite dish on the ground
How do mobile phones use microwaves?
Mobile phone calls travel as microwaves between your phone and the nearest transmitter. Some wavelengths of microwaves are absorbed by water molecules and heat them up
Microwaves are used by remote-sensing satellites. What do remote-sensing satellites do?
They ‘see’ through the clouds and monitor oil spills, track the movement of icebergs, see how much rain forest has been chopped down etc.
What are infrared waves used for?
Remote controls and optical fibres
How are infrared waves used for Remote controls?
Remote controls work by emitting different patterns of infrared waves to send different commands to an appliance
How are infrared waves used for optical fibres?
Optical fibres carry data over long distances very quickly.
They use infrared and visible light
The signal is carried as pulses of light/infrared radiation and is reflected off the sides of a very narrow core from one end of the fibre to the other
How is visible light used in photography? How do cameras work?
Cameras use a lens to focus visible onto a light-sensitive film or an electronic sensor
The lens aperture controls how much light enters the camera (like a pupil)
The shutter speed determines how long the film/sensor is exposed to the light
By varying the aperture and shutter speed (and sensitivity of the film/sensor) a photographer can capture as much light as they want in their photograp
