waves and energy transfer 14.1 wave properties wave a repeating disturbance or movement that...
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Waves and Energy Transfer
14.1 Wave Properties
Wave
• A repeating disturbance or movement that transfers energy through matter or space
Mechanical Waves
• Require a medium
• Can be Transverse and Longitudinal
Electromagnetic Waves
Do NOT need a medium to travel throughElectromagnetic waves are Transverse waves
Electromagnetic Wave
• A disturbance (wave) in electrical and magnetic fields
• Does not require a medium
Types of
Matter Wave
• Wave-particle duality of matter
• Quantum Mechanics
Transverse Waves• Disturbance is perpendicular to the direction of
travel
Longitudinal Waves• Disturbance is parallel to the direction of travel
• AKA Compressional waves
• All longitudinal waves are mechanical waves
Water Surface Waves• Both transverse and
longitudinal
Wave Pulse• A single disturbance that travels through a medium
The Measures of a Wave
Crest & Trough
Wavelength
• The distance from crest to crest
• One Cycle
• Lambda
The Period
• The amount of time it takes for one complete cycle
Frequency
• 1 Hz is 1 wave per second
The number of waves per secondMeasured in Hertz (Hz)
Wave Velocity
Amplitude• The Height of the wave
• Equals the wave energy
Behavior of Waves
• Diffraction
• Refraction
• Reflection
• Interference• Constructive• Destructive
Interference • Two or more waves traveling through a medium at the same time
• Constructive – increases amplitude
• Destructive – decreases amplitude
Standing Waves
• Node• Antinode
Reflection• Normal line – right angle to barrier• Angle of Incidence• Angle of Reflection
The Law of Reflection
Refraction
• The change in the direction of a wave at the boundary of two different media
Diffraction
The bending of a wave around an obstacle or an edge
SoundProperties of Sound
Sound Waves• Sound waves are longitudinal (compressional) waves
in matter
If a tree falls in a forest and no one hears it, does it make a sound?
Loudness and Pitch
Amplitude
Frequency
Velocity of Sound Waves
• Depends on the medium and the temperature
Reflection of Sound Waves
• Echo
Doppler Effect• The apparent change in the frequency (pitch) of
waves because of the relative motion between an observer and the wave source
Doppler Effect Equation:Calculate observed frequency of an object moving toward a stationary observer
While standing near a railroad crossing, a person hears a distant train horn. According to the train's engineer, the frequency emitted by the horn is 440 Hz. The train is traveling at 20.0 m/s and the speed of sound is 346 m/s.What is the observed frequency that reaches the bystander as the train approaches the crossing?
467 Hz
Red Shift and Blue shift
Sonic Boom• A shock wave caused by merging sound waves
Sound Level
• Decibels• 10-dB is
twice as loud
LightLight Fundamentals
Electromagnetic Radiation• Visible light wavelength 400-700 nm
Wave lengths of visible light• Different
wavelengths of light equal different colors
• ROYGBIV
The speed of Light• And all other
EM waves
Photon• A particle of light
Sources of LightLuminous Body
• Emits light wavesIlluminated Body• Reflects light
Incandescent Object• Emits light because it is extremely hot
Luminous Flux (P)• The rate at which light is emitted• A 100-watt bulb emits 1750 lumen
Illuminance (E)• The Illumination of a surface• Lumens per square meter (lux or lx)
Illuminance equation• P is the lumens
Inverse Square Law• If the distance doubles, the intensity decreases by a
factor of 4
Candela (cd)• A measure of luminous intensity
• Increase flux, decrease distance
• The SI unit for light intensity
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