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Properties of Waves Waves are characterized by two numbers: Wavelength, (size of the wave) Frequency, ν (number of waves/second) For sound waves, frequency more commonly called pitch For light waves, these are all related by: c = ν Where c is the speed of light Longer means Smaller ν
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The Doppler Effect
Shown by all types of waves
Properties of WavesWaves are characterized by two numbers:
• Wavelength, (size of the wave)
• Frequency, ν (number of waves/second)For sound waves, frequency more commonly
called pitch
For light waves, these are all related by:
c = νWhere c is the speed of light
Longer means Smaller ν
Electromagnetic Wave
MagneticField
ElectricField
The Doppler EffectShift in the observed wavelength when the source is moving relative to the observer.
Examples:• Sound Waves (Siren or Train Horn)• Light Waves
Amount of the shift and its sign depends on• relative speed of the source & observer• direction (towards or away)
Stationary Source
Same Pitch Same Pitch
Doppler Effect in Sound
High Pitch(short waves)
Low Pitch(long waves)
The Doppler Effect in LightWorks same as it does for sound
Light moving away from the observer Wavelength gets longer: REDSHIFT
Light moving towards the observerWavelength gets shorter: BLUESHIFT
Way to Measure SpeedsObserve the wavelength (obs) of a source with a known emitted wavelength (em)
The difference is directly proportional to the speed of the source, v:
obs
em
vc
- = em
Use on Earth