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 through Electromagnetic 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 second Measured 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

Sound Properties 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

Light Light Fundamentals

Electromagnetic Radiation Visible light wavelength 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 Light Luminous Body Emits light waves Illuminated 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

Transparent Translucent Opaque