Electromagnetic Waves Flashcards
what ar 10 properties of EM waves?
1) transverse waves
2) can travel in vacuum
3) travel at light speed in vacuum
4) transfer energy from one place to another
5) obey general wave equation
6) speed and wavelength change when travelling into different media
7) obey laws of reflection and refraction
8) do not carry electric charges
9) produced when a charge is accelerated
10) ionising waves have higher frequencies and thus higher energy
what are the regions of the EM spectrum in order of increasing frequency/decreasing wavelength?
radio waves (10⁻¹ to 10⁴ m)
microwaves (10⁻³ to 10⁻¹ m)
infra-red radiation (10⁻⁷ to 10⁻³ m)
visible light (4x10⁻⁷ to 7x10⁻⁷ m)
ultraviolet radiation (10⁻⁸ to 10⁻⁷ m)
x-rays (10⁻¹⁰ to 10⁻⁸ m)
gamma rays (<10⁻¹¹ m)
what are the uses of radio waves?
radio/TV communication
radio astronomy
Radio Frequency Identification (RFID) tags
what are the uses of microwaves?
mobile phones
microwave oven
satellite television
what are the uses of infra-red radiation?
infra-red remote controllers
intruder alarms
thermal imaging
what are the uses of visible light?
optical fibres for medical uses and telecommunication
photography
what are the uses of ultraviolet radiation?
sunbeds
bank note authentication
disinfecting water
what are the uses of X-rays?
medical radiology
security screening
industrial defect detection
what are the uses of gamma rays?
sterilising food
detection of cancer and treatment
how do ionising radiations harm our bodies?
- high frequencies, high energy
- penetrate our bodies easily to destroy/modify living cells/tissue
- charged ion behaves differently from normal, hindering chemical reactions and affecting certain cell purposes
- exposure to strong EM radiation like UV causes heating effects and over-exposure can cause skin cancer/premature aging
