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CHAPTER 17&18 NOTES

This article provides a comprehensive overview of waves, including their characteristics, types, and interactions. It covers topics such as transverse and longitudinal waves, reflection, refraction, diffraction, and the Doppler effect. The article also explains the production of sound waves and explores concepts like intensity and loudness.

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CHAPTER 17&18 NOTES

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  1. CHAPTER 17&18 NOTES KONICHEK

  2. I. WAVE- A rhythmic disturbance through matter or space • A. Medium- any matter through which the wave travels through • B. Mechanical wave- waves which require a medium

  3. II. Light waves • A. Travel through empty space • B. Travel at 3x108m/s • c. Called electromagnetic waves • 1. Visible light, others • 2.Combination of 2 forces, the electrical and magnetic forces vibrating at right angles to each other

  4. III. WAVES TRANSFER ENERGY • A. Waves have the ability to do work. • 1. Sound on eardrum • 2. Tsunami/Tidal waves

  5. IV. ENERGY SPREADS OUT AS A WAVE TRAVELS • A. As distance increases a sound wave loses some of it’s energy • 1. Energy spreads out over distance,

  6. V. VIBRATIONS AND WAVES • A. Waves are related to vibrations. • 1. Vibrations are created by energy • B. Vibrating objects produce waves • C. Vibrations involve transformation of energy. • 1. Oscillating spring • D. Waves can pass through a series of vibrating objects. • 1. The Ke of the wave can pass through Harmonic motion

  7. VIBRATIONS CAUSE WAVES

  8. VI. Transverse and Longitudinal waves • A. Transverse wave- A wave which vibrates at right angles to the direction it moves • 1. Water wave, light waves • B. Longitudinal waves- waves which vibrate in the same direction as they move • 1. Sound wave

  9. TRANSVERSE WAVE

  10. SOUND WAVE- LONGITUDINAL WAVE

  11. VII. Surface wave-occurs on the boundary area between different mediums • A. Move both perpendicular and parallel ( water waves)

  12. VIII. CHARACTERISTICS OF WAVES • A. wave properties • 1. All transverse waves look about the same • a. Sine curve- S shaped • 1. Sine wave- Waves which are made up of Sine curves.

  13. 2. Crest- highest point if a wave 3. Trough- the lowest point of a wave

  14. 4. Amplitude- This is the height of a wave from a fixed point( normal) • a. Determines the amount of energy in a wave. • 5. Wavelength- the distance from one point on a wave to the same point on the next wave • a, Units are cm, angstroms, nanometers

  15. AMPLITUDE – THIS IS THE HEIGHT- DETERMINES ENERGY

  16. WAVELENGTH

  17. WAVELENGTH DETERMINATION

  18. 6. frequency- The number of waves past a point in one second • a. Units Hertz( Hz) • b. Wave Speed= wavelength x frequency • 1. Depends on the medium • a. Sound waves

  19. B Kinetic theory- the structure of the matter will determine the speed • a. solids, liquids, gases-- examples • C. Speed of light is finite 3x108m/s • 1. 7 ½ times around the Earth in 1 second

  20. D. Doppler effect- The apparent change in frequency of the wave caused by the motion of the source or the observer • 1. Towards the source - wavelength is shorter( blue, higher pitch) • 2. Away from the source- wavelength is longer( red or lower pitch)

  21. DOPPLER EFFECT

  22. IX. wave interactions • A. Reflection- The bouncing of a wave off a barrier. • 1. Incident wave-source to barrier • 2. Reflective wave-barrier to detector • 3. Angle of incidence-angle formed from the normal to source • 4. Angle of reflection-angle formed from the normal to detector • 5. Law of Reflection- the angle of incidence equals the angle of reflection

  23. B. Diffraction-The bending of a wave around a barrier. • 1. Diffraction gratings- pieces of glass or plastic with many parallel slits • a, Spreads out white light into the spectrum • b used to determine the composition of celestial objects

  24. REFLECTION

  25. REFLECTION OF SOUND-ECHO

  26. C. Refraction- The bending of light as it passes from one medium to another • 1. Change in the speed of the wave

  27. REFRACTION OF LIGHT

  28. REFRACTION IN WATER

  29. SEPERATION OF WHITE LIGHT

  30. D. Interference- The result of when waves collide • 1. Constructive- crest meets crest and troughs meet troughs • a. Waves reinforce each other • 2. Destructive- crest meets trough • a. Cancel each other out. • 3.standing waves-The reflected wave have the same amplitude, speed and frequency. • a. Don’t move through the medium- cause the medium to vibrate

  31. Constructive Interference

  32. DESTRUCTIVE INTEREFRENCE

  33. X SOUND WAVES • A. PRODUCING SOUNDS • 1. VIBRATION -Needs energy- The back and forth motion of matter • B Sound wave- a longitudinal wave produced by a vibration in a medium • C. SPEED OF SOUND- Depends upon the medium, it’s traveling through, and the temperature of the medium • 1. in air at 20 degrees Celsius 340m/s • 2. in solids 15 times faster • 3. in liquids 4 times faster • D. The speed of sound changes as the temperature of the medium changes • 1.speed increases or decreases .6m/s for each degree Celsius

  34. XI. INTENSITY AND LOUDNESS • A. Loudness is the perception of the rate at which sound energy enters the ear. • B. Intensity- The actual measurement of the rat-. high intensity waves produce large amplitude and this produces a loud sound. • C. Intensity level- measured by comparing sounds to the lowest possible sound heard by humans • 1. measured in decibels( dB) • a. breathing =10 dB, chain saw =115dB

  35. XII. DANGERS OF SOUND A. intensity levels over 90dB cause permanent ear damage B. a single exposure over 150 dB can break the eardrum. 1, ear protection in places which are extremely loud C. Noise- bothersome, harsh, unappealing sounds. 1. noise pollution- an excess of unwanted sounds

  36. XII FREQUENCY AND PITCH • A. Pitch- the ears perception of frequency • 1. high frequency= high pitch • 2, low frequency= low pitch • B. Ranges of frequency • 1. humans- 20 to 20,000 hz • 2. dogs- 15 to 50,000 • 3. bats 1000 to 120000 • C ultrasonics- sounds above the human range of hearing.

  37. XIV. SOUND WAVE BEHAVIOR • A. echoes- the reflected sound wave is an echo • 1. echoes can’t be detected if the time between the sound and the echo is at least .05 seconds. • B. Sonar- Uses the reflection of sound waves as an information gathering process. SOUND NAVIGATION AND RANGING • C. DIFFRACTION OF SOUND

  38. C. DIFFRACTION OF SOUND • 1. sounds bend around corners rather easily because of their long wavelength • D. Refraction of sound waves- Sound traveling through differnt densities of air. • 1. during the day sounds don’t travel as far because of the warm air refracting the sounds upward, • 2. at night the warm air above refracts the sounds downward so the sounds seem like thet travel farther

  39. XIII. HEARING • A. regions of the ear- outer, middle and inner • 1. outer ear is fleshy and funnels sounds into the eardrum • a. eardrum- a tympanic membrane which vibrates when struck by sounds • 2. Middle ear- 3 bones composition • a. hammer( malleus) • b. anvil( incus) • c. stirrup( stapes) • 3. Inner ear- Cochlea and semicircular canels • a. changes the mechanical sound wave into the electrical impulse which is sent to the brain.

  40. The ear-who’s listening?

  41. VI. MUSIC A. Regular patterns of sound B. Musical inturments- produce sounds by vibrating strings or columns of air, or vibrating membranes 1. rely on standing waves.

  42. C, Classification of instruments 1. strings- Use a vibrating string and a resonating cavity a. pitch depends on the diameter and the length of the string 2. Woodwinds- Use a vibrating reed, and pitch is changed by changing the length of the column of air

  43. 3.BRASS- The lips vibrate and the pitch is changed by using a slide or keys which change the lengt of the air column 4. drums- they keep a beat a. Tympany- able to change the pitch by regulating te tightness of the membrane D. Resonance-The vibrating of the body of the insturment at the same frequency as the nusical notes being played.

  44. VIII.ULTRASOUND AND SONAR A. SONAR- SOUND NAVIGATION AND RANGING 1. used to determine the depth of waters, and schools of fish 2. distance calculations from time. a. D=VT, V is the velocity of sound in water, T is the time it takes for the return wave.

  45. IX. ULTRASOUNDS IN MEDICINE a. In pregnancies to detect any defects b. Echogram of the heart to see if the muscle is fully functioning c. Advantages- does subject tissue to x-ray radiation which may cause tissue damage d. High frequency waves can pass through soft tissue very easily

  46. CHAPTER 18 NOTES • XIV. NATURE OF LIGHT • A. Theories on the composition of light ' • 1. Wave model-Light travels in waves a. interference patterns like a wave- Young’s observation b. transverse wave-electromagnetic in nature • c. electric and magnetic waves vibrating at 90 degrees to each other • d. Einstein's photoelectric effect- won the noble prize for the discovery ( EARLY QUANTUM THEORY) • 1. Problem- why do electrons fly off metal when struck by high energy light

  47. 2. Particle theory of light- Light occurs in nature as discreet little bundles of energy • a. photon-a packet of radiant energy. • b. No mass • c. Energy of the photon is dependant on the wavelength of light • 2. Light is weird- sometimes it acts like a wave, other times acts like a particle.

  48. B. Energy of light is proportional to the frequency of the light. • 1. high frequency short wavelength high energy- Blue light. • C. Speed of light depends on the medium-3xlO8 m/s in space. • 1. according to most scientists is the speed limit of the universe- special relativity. • 2. E=mc2 • D.Light intensity- the quantity which measures the amount of light illuminating a surface • 1. obeys the inverse square law. I=1/d2

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