Properties of waves and EM spectrum Flashcards
Order of waves from long to short wavelength(low to high frequency)
-Sing the song
Radio waves, Microwaves, Infrared (radiation), Visible Light, Ultraviolet, X-rays, Gamma rays
What is the EM spectrum
A continuous range of wavelengths/frequencies of electromagnetic waves/radiation (with different uses)
How fast do all these waves travel
300,000,000 m/s
Uses and dangers of Radio waves
1 Broadcasting on radio or TV
2 communication and satellite transmission
3 Radar
- heats up body tissue
Uses and dangers of Microwaves
1 Microwave ovens (heating foods)
2 Satellite communication
-heats up body tissue (specifically water)
-burns
Uses and dangers of Infrared
1 heating
2 thermal imaging
3 remote controls
-heating
-skin absorption
Uses and dangers of Visible Light
- seeing and taking photos
- Fibre optic communications
-eye damage
Uses and dangers of Ultraviolet
1 fluorescent lights
2 sterilisation
3 verifying money, ID, passports
-skin damage (sunburns)
-eye damage (cataracts)
skin cancer (wear sun cream)
Uses and dangers of X-rays
1 medical imaging
2 security screening
-damage cells
-ionising radiation can cause cancer risk
-acute radiation sickness
can be blocked by lead screen
Uses and dangers of Gamma rays
1 medical imaging
2 cancer treatment
-damage cells
-ionising radiation can cause cancer risk
-acute radiation sickness
can be blocked by lead screen or sometimes concrete
Similarities of all EM waves
All travel at speed of light
All transverse waves
All waves can be:
Reflected and refracted
Law of reflection
Angle of incidence (i) = Angle of reflection (r)
Less dense to more dense
Light bends towards normal
More dense to less dense
Light bends away from normal
Passing along the normal
Light does not bend at all
Snell’s Law
n (refractive index) = sini/sinr
Doppler Effect definition
The apparent change in wavelength and frequency of a wave emitted by a moving source
Explain the Doppler Effect
-Usually when a stationary object emits waves, the waves spread out symmetrically
-When the object moves, the waves get squashed together at one end, and stretched at the other end
-To an observer at the front of the object, the wavelength appears to be smaller and vice versa
= The wavelength decreases at the front (and vice versa)
How do ray guns measure the speed of a car
The ray gun emits a wave that reflects off the car
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