P13 Electromagnetic waves Flashcards
List the electromagnetic spectrum from the longest wavelength to the shortest wavelength (7)
Radio waves, microwaves, infrared, visible light, ultraviolet, x-rays and gamma rays
What do electromagnetic waves do?
Transfer energy from a source to an absorber
What is the wave speed for all electromagnetic waves?
3 x 10^8 m/s
What is the part of the electromagnetic spectrum that is detected by our eyes?
Visible light
What is infrared radiation emitted by?
It is emitted by all objects, the hotter the object the more IR it emits
What are radio waves used for?
To transmit radio and TV programmes
What are microwaves used for?
Used in communications. They produce wavelengths that are able to pass through the atmosphere. Used to send signals to and from satellites and to heat food
What are carrier waves?
Waves that carry any type of signal
What does a wavelength being shorter effect?
The shorter the wavelength the more information they can carry, the shorter their range, the less they spread out
What types of waves can optical fibres carry?
Visible light or infrared radiation
Why are optical fibres useful?
They are useful in communication as the waves stay in the fibre
What are ultraviolet waves used for?
Security marking, and sun beds, can cause sun burn and skin cancer
What are x-rays used for?
To make images of bones and detect cracks in metal objects
What are gamma rays used for?
To kill harmful bacteria in food and to sterilise surgical equipment
What is ionisation?
When electrons are knocked out of atoms, leaving the atoms with a positive charge
