P15 Electromagnetic waves Flashcards
What type of wave are electromagnetic waves?
Transverse
Explain why EM waves are not mechanical waves
Because they can travel through a vacuum
What do EM waves transfer from their source to an absorber?
Energy
Name the electromagnetic spectrum going from longest wavelength to shortest wavelength
Radio waves
Microwaves
Infrared
Visible light
Ultraviolet
X-rays
Gamma rays
What part of the EM spectrum can humans see?
Visible light
How can electromagnetic waves be produced?
Changes inside of an atom / atomic nucleus
How are gamma rays produced?
Changes in the nucleus of an atom
e.g during radioactive decay
How can radio waves be produced?
Oscillations in an electrical circuit
How can we detect radio waves?
Waves are absorbed and create an alternating current with the same frequency as the radio wave
Uses of radio waves
TV and radio signals
Why are radio waves suitable for their use?
Can travel a long distance through air
Longer wavelengths can bend around obstructions to allow detections of signals
Uses of microwaves
Satellite communications
Cooking food
Why are microwaves suitable for their use?
They can pass through the Earth’s atmosphere to reach satellites
Can penetrate into food and are absorbed by water molecules in food, heating it
Hazards of microwaves and radio waves
Can penetrate the body and cause internal heating
Uses of infrared waves
Electrical heaters
Cooking food
Infrared cameras
Why are infrared waves suitable for their uses?
Can transfer energy quickly to heat rooms and food
Sensors can detect infrared waves and turn them in to images
Hazards of infrared waves
Can damage or kill skin cells due to heating
Uses of visible light waves
Fibre optic communications
Why is visible light suitable for its use?
Short wavelength means that visible light carries more information
Hazards of visible light
Can damage the retina
Uses of ultraviolet waves
Energy efficient light
SUNBEDS
Why are ultraviolet waves suitable for their uses?
Carries more energy that visible light
Hazards of ultraviolet waves
Can damage skin cells
Increases risk of skin cancer
Can cause blindness
Uses of X-Ray waves and gamma rays
Medical imaging and treatments
Why are X-rays and gamma rays suitable for their use?
Can easily pass through flesh but not bone
High doses kills living cells such as cancer cells
Gamma rays can also kill harmful bacteria
Hazards of X-rays and Gamma rays
Form of ionising radiation
-can damage or kill cells
Causes mutations of genes
What is refraction?
Waves change speed and direction as they cross the boundary from one substance to another due to change in velocity
What happens to the direction of a refracted EM wave when it slows down as it crosses the boundary from one substance to another?
Bends towards the normal
