P12- Electromagnetic Waves Flashcards
What type of wave are electromagnetic waves?
Transverse
Why are em waves not mechanical?
They can travel through a vacuum
What do elm waves transfer?
Energy
What is the em spectrum, from highest to lowest wavelength
Radio, microwave, infrared, visible light, uv, x rays, gamma
How are em waves produced?
Changes in an atom
How are gamma rays produced?
Changes in the nucleus of an atom
How are radio waves produced?
Oscillations in an electrical circuit
How are radio waves detected?
Waves are absorbed and create an alternating current with the same frequency as the radio wave
What are radio waves used for?
Transmitting tv, radio and, mobile phones and Bluetooth
Why are radio waves used?
Cam travel long distances through air
Longer wavelengths can bend around obstacles and can be detected without being in the line of sight
What are microwaves used for?
Satellite communications and cooking food
Why are microwaves used?
Can pass through the atmosphere
Can penetrate into food
What are the hazards of micro waves and radio waves?
Can penetrate the body and can cause internal damage
What are infrared waves used for?
Electrical heaters, cooking food and infrared cameras
Why are infrared waves used?
Transfer energy quickly to heat rooms and food
Sensors can detect the infrared waves to turn them into images as all hot objects emit infrared radiation
What are the dangers of infrared radiation?
Can damage or kill skin cells
What is visible light used for?
Fibre optic cables
Why is visible light used?
Short wavelength means it can transfer information
Can bend around corners
What are the risks of visible light?
Can cause eye damage
What are the uses of UV?
Artificial tanning
Energy efficient lights
Why is UV used?
Carries more energy than visible light
What are the dangers of UV?
Can damage skin cells, risk of cancer, blindness
What are x rays and gamma rays used for?
Medical imaging and treatments
Why are x rays and gamma rays used?
Pass easily through flesh, but not denser materials such as bone
Can be used to kill cancer cells as high doses kill cells
Gamma used to kill bacteria
What are the dangers of using gamma and x rays
Form ionising radiation, which can damage cells and cause cancer
What is refraction?
Waves change speed and direction as they cross a boundary from one substance to another due to a change in velocity
