II. Types of Waves A. Transverse waves 1. Can travel with or without matter (medium)

Transcription

1 SOL: PS. 8 & 9

2 I. Waves A. Definitionà a disturbance that transfers energy through matter or space II. Types of Waves A. Transverse waves 1. Can travel with or without matter (medium)

3 2. Moves at rt. angles to the direction it travels (moves up and down as it goes) 3. Exampleà light (electromagnetic waves)

4 4. Parts of a traverse wave A. crest B. trough C. wavelength D. amplitude E. wave height F. line of origin (at rest)

5 B. Compression (Longitudinal) Wave 1. must travel with matter (medium) 2. moves in the same direction as it travels 3. Exampleà sound (caused by vibrations)

6 4. Parts of a compression wave x. compression y. Rarefaction z. wavelength

7 C. Similar Parts 1. compression à crest 2. rarefaction à trough

8 III. Wave Properties A. Amplitude measure of the amount of energy in a wave 1. Sound a. determines intensity/loudness b. units à decibel (db) c. possible hearing damage occurs at 120 db

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10 2. Light a. the greater the amplitude the brighter the light

11 B. Frequency - measures how often waves pass a certain point 1. measured in units called hertz (Hz) 2. Sound a. Pitch the highness/lowness of sound b. Human hearing rangeà 20 Hz 20,000 Hz

12 Pitch 200 Hertz 400 Hertz 600 Hertz 800 Hertz 1,000 Hertz 5,000 Hertz 10,000 Hertz

13 3. Light a. As you move across the spectrum, wavelength decreases and frequency increases The Electromagnetic Spectrum

14 C. What is the relationship between wavelength and frequency? 1. If wavelength increases then frequency decreases 2. If wavelength decreases then frequency increases

15 IV. Wave Interactions/Movements A. Reflectionà when a wave bounces off a surface 1. Angle of incidence = angle of reflection 2. Examples a. Sound- Echo

16 b. Light- looking in the mirror; sight

17 B. Refraction à bending of a wave as it changes speed 1. Example-a pencil in glass of water looks broken

18 2. Example- prism bends white light into the spectrum of colors (rainbow) (refraction of white light)

19 C. Diffraction à bending of a wave around an object 1. Example water waves bend around people 2. Example hear sounds from another room

20 Diffraction

21 D. Interferenceà interaction between 2 waves at the same place and time (waves combine) 1. Constructiveà makes a bigger wave; increases intensity; results in louder sound/brighter light

22 2. Destructive à makes a smaller wave; decreases intensity; results in softer sound/softer light

23 F. Resonance à object vibrate at its natural frequency; applies to sound Ex. Tuning fork, guitar strings, bridge swinging due to high winds (Tacoma Narrows Bridge)

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25 V. Properties of Sound A. Sound Barrier 1. Definition à point when an object moves faster than the speed of sound 2. Sonic Boom the sound made when something breaks the sound barrier 3. October 14, 1947 Chuck Yeager breaks the sound barrier

26 B. Doppler Effect 1. Refers to changes in pitch as an object approaches 2. Examples include ambulance/police sirens, car horns

27 C. Uses of Sound 1. Major (common) uses include communication, warning signals, and entertainment

28 2. Other uses of sound include: a. Infrasound (subsonic) à refers to sounds below 20 hertz (Hz) * used to detect earthquakes, find oil b. Ultrasoundà refers to sounds above 20,000 hertz (Hz) * used in- sonograms, removal of kidney stones, and dog whistles

29 3. Echolocationà use of reflection to locate objects; bats, dolphins 4. SONARà Sound Navigation and Ranging; used to locate objects under water 5. Acousticsà study of sound

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32 D. Speed of soundà about 345 m/s in air; speed of sound affected by: 1. temperature- faster in warmer temps 2. density- faster in solids than is liquids and gases

33 SOL: PS. 9

34 VI.Properties of Light A. What is light? 1. Light is an electromagnetic, transverse wave caused by vibrating electric charges 2. Speed of light - 300,000 km/s (186,000 miles/s); light year distance light travels in one year

35 3. Light Controversy-Particle or Wave? a. Difference between waves and particles is not clear. b. Light can behave like a packet of energy called a photon c. Quantum Theory proved it is both a wave and a particle

36 B. The Electromagnetic Spectrum - Represents the entire range of visible and invisible light waves The Light Spectrum

37 Uses of Electromagnetic Waves 1. Radio Waves- lowest frequency, longest wavelengths, lowest energy AM FM TV (AM for sound + FM for pictures)

38 2. Microwaves shorter radio waves Cooking Satellite communications MRIs Cell phones RADAR

39 3. Infrared waves felt as heat Night vision/thermal imaging CD players Video games Check out scanners and TV remotes

40 4. Visible Light can be seen with the eye R ed O range Y ellow G reen B lue I ndigo V iolet

41 5. Ultraviolet (UV) waves sun s rays Most is absorbed by the ozone layer Prolonged exposure can cause sunburn and lead to cancer Can be used to kill bacteria

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43 6. X-ray waves * used to photograph bones * used to examine suitcases at airports

44 7. Gamma Rays has highest frequency, shortest wavelength, and the most energy *used for radiation treatment for cancer

45 C. The Behavior of Light 1. Objects must reflect light to be seen; the reflection of light determines the color you see. 2. Opaque materials do not allow light to pass through; no images 3. Translucent some light passes through it; fuzzy image 4. Transparent all light passes through it; clear image

46 5. Objects that reflect light are Illuminated * Ex. Moon Objects that make their own light are Luminous * Ex. Sun

47 Bioluminous- organisms produces its own light * Ex. Angler fish, glow worm, fire fly

48 6. Light and Color a. Color à determined by wavelength of light an object reflects b. Objects appear to be white because they reflect all colors of visible light c. Objects appear to be black because they absorb all colors of visible light d. Filter à transparent material that absorbs all colors except the color(s) it transmits

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50 D. Light Optics 1. Common Uses of Light- light bulbs, lasers, fiber optics, optical scanners *Incandescent à produce light and heat *Fluorescent à electricity passes through a gas that produces light *Neonà gases produce light with different colors

51 Lasers- amplified beam of light * Ex. CDs, surgery, security

52 Fiber Optics for communication Optical scanners- read reflected light; Ex. Copiers, bar code readers, cameras

53 2. Lens à transparent device usually made of glass or plastic that refracts light a. Convex Lens b. Concave Lens

54 3. Mirror à device with curved surfaces designed to reflect light

55 Concave mirrors converge light and produce an upright, magnified image if close and an inverted, smaller image if far away. Convex mirrors diverge light and produce a smaller, upright image.

56 4. Telescope à uses mirrors and lenses to see far away objects 5. Microscope à uses 2 convex lenses to magnify objects