Electromagnetic Waves Flashcards
What are electromagnetic waves made up of?
Oscillating electric and magnetic fields, they oscillate perpendicularly to the direction of propagation of the electromagnetic wave
T/F Do electromagnetic waves carry charges
They do not carry electric charges
Describe how to find speed of electromagnetic wave in medium
- v = fλ where v is speed, f is frequency and λ is wavelength
- speed of em wave in vacuum is 3.0*10^8
State electromagnetic wave with longest wavelength
Radio waves
State order of electromagnetic waves from lowest frequency to highest
Radio waves, microwaves, infrared radiation, visible light, ultraviolet radiation, x-rays, gamma rays
What are uses of radio waves
- Television and radio communication
- Radio telescopes for radio astronomy to study radio frequencies from outer space
What are uses of microwaves
- Microwave oven
- Wi-Fi signals
- Mobile phone communication
- Global Positioning System and radar
What are hazards of microwaves
Heating effect
What are uses of infrared radiation
- Remote control
- Intruder alarm
- Thermal imaging
- Camera auto-focusing
- Infrared thermometer
What are the uses of visible light
- Photography
- Optical fibres in medicine and telecommunication
What are the uses of ultraviolet radiation
- Sterilisation of medical equipment
- Disinfection of water in water treatment plants
- Sunbed for artificial tanning
- Counterfeit bank notes checking
What are hazards of ultraviolet radiation
Prolonged exposure can lead to sunburns, premature aging and increased risk of skin cancer
UV radiation can be ionising
What are uses of X-rays
- Scan for manufacturing defects in metal parts
- Scan luggage for prohibited items at airports
What are uses of gamma rays
- Gamma imaging to detect cancer
- Radiation therapy to treat cancer
- Sterilisation of medical equipment and food
What are the hazards of gamma rays
Ionising radiation
Exposure can damage biological molecules, living cells and tissues, leading to cell death, mutations and abnormal cell division
May cause cancers and deformities to developing foetus
