2Waves Wave: a disturbance that transfers energy from place to place. Medium: the material through which the wave can pass.Waves are classified by:1. the way they move.2. the medium through which the wave can pass.
3Transverse waves: Particles of the medium move perpendicular to the direction of wave motion.(looks like a jump rope)2. Can travel through liquids, gases, empty space and SOME solids.Ex) Ocean waves
4Longitudinal Waves Particles of the medium move parallel to the direction of wave motion.(looks like a slinky)Ex) sound and water
6CrestCrest - maximum positive distance from the rest position, top of the wavePeak
7TroughCrest - maximum positive distance from the rest position, bottom of the waveValley
8AmplitudeAmplitude - the height of the wave, either rest position to crest or rest position to troughAmplitude is 1/2 the total displacementTells the strength, power, intensity of a waveEx: sound - volume, light - brightness, earthquakes - powerUnits = Meters
9WavelengthWavelength - the distance from one corresponding point on a wave to the same point on the next waveCrest to crest, or trough to troughUnits are Meters
10FrequencyFrequency - the number of waves that pass a fixed point in a given amount of timeGreater frequency, greater the energyUnits are waves per second, Hertz (Hz)
11VelocityVelocity - the speed and direction of the wave, distance divided by timeUnits are m/sThe velocity of a wave changes in every new medium it entersMedium - the material a wave is traveling throughSound travels at ~343 m/s and light at ~300,000,000 m/s
12Velocity = frequency x wavelength Wave FormulaWave formulav = f x wVelocity = frequency x wavelengthEx: A wave traveling at 3.0x108 m/s has a frequency of 10,000Hz. What is the wavelength of the wave?3.0x108 m/s = 10,000Hz x ww = 3.0x108 m/s / 10,000Hz = 30,000m
13ReflectionReflection - waves strike a surface they reflect and invert.Ex: Sonar - sound, radar - radio waves, echoes for sound, satellites
14Part 2 - Reflection Reflection from a mirror: Mirror Normal Incident rayReflected rayAngle of incidenceAngle of reflectionMirror
15Only red light is reflected Seeing colorThe color an object appears depends on the colors of light it reflects.For example, a red book only reflects red light:HomeworkWhitelightOnly red light is reflected
16A white hat would reflect all seven colours: A pair of purple trousers would reflect purple light (and red and blue, as purple is made up of red and blue):Purple lightA white hat would reflect all seven colours:Whitelight
17A white hat would reflect all seven colours: A pair of purple trousers would reflect purple light (and red and blue, as purple is made up of red and blue):Purple lightA white hat would reflect all seven colours:Whitelight
18In different colours of light this kit would look different: RedlightShirt looks redShorts look blackShirt looks blackBluelightShorts look blue
19RefractionRefraction - waves bend when entering a new medium, the change in density causes the wave to change speedEx: Pencil bends in water, fish look bigger in water
22Diffraction Diffraction - waves bend around an obstacle in their path Ex: sound can bend around corners, light can fan out through small openings
23InterferenceInterference - two or more waves traveling in the same medium can interact. They can reinforce each other called constructive interference (in-phase) or oppose each other called destructive interference (out-of-phase)Ex: Waves can add or subtract to form a new wave (Rogue wave in ocean)
24The Doppler EffectDoppler Effect - change in frequency of a wave based on the motion of the source or observerthe frequency of a wave appears higher when approaching and lower when moving away from the observerWorks for all waves
25Doppler Effect - SoundSounds appear higher in frequency (pitch) when approaching and lower when moving awayEx #1 - An police siren sounds higher frequency (pitch) when approaching and lower when moving away
26Doppler Effect - LightLight appears higher in frequency (closer to purple) when approaching and lower (closer to red) when moving awayEx #2 - Light appears higher frequency when approaching (Blue-Shift) and lower frequency when moving away (Red-Shift). Hubble proved the universe is expanding because light is shifted towards the red frequencies.
27SoundSound - mechanical wave caused by objects vibrating, which compresses and expands air moleculesSpeed of sound increases with temperature
28Sound - CompressionalCompressional (longitudinal) wave, moves faster through dense objects, can’t go through a vacuum
31The Electromagnetic Spectrum Electromagnetic waves - energy caused by vibrating charged particles such as electronsAll move the speed of light = 3.0 x 108m/sCan travel through nothing at all (vacuum), and go faster through less dense mediumsAre ordered based on energy, frequency, and wavelengthOrder: radio, microwaves, infrared (heat), visible light, ultraviolet, x-rays, and gammaROYGBIV are the colors of visible light
32Electromagnetic continued… Energy of electromagnetic waves are electron volts (eV)We only see the colors of visible light, but many of the other waves can be detected with special instruments, some animals don’t see with visible light (insects, reptiles)Overexposure to the waves higher in energy than visible light (UV, x-ray, and gamma) can be harmful causing cancer and genetic mutationsElectromagnetic energy is often aborbed into heat
33Daily Quiz Questions #1-5 labels the parts of the wave on the board 6. What is it called when a wave bends in a new medium?7. What is it called when a wave bounces off a surface?8. What is it called when a wave bends around an obstacle?
34Daily Quiz9. What part of the wave tells you the intensity of the wave?10. What is the length of the wave called?11. What is the number of waves per second called?12. What are the units for wavelength?13. What are the units for frequency?
35Daily Quiz14. Which type of wave vibrates parallel to the direction it travels?15. Which type of wave vibrates perpendicular to the way it travels?16. True or False. Sound is produced by vibrating objects.17. True or False. Sound can travel through a vacuum.Bonus #1 - What is the change in frequency called when an object approaches and leaves/Bonus #2 - What does Mach 2 mean (Think sound)?