IPC Waves, Sound, Light and Optics

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IPC Waves, Sound, Light and Optics

• C. Smith

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Waves, Sound, Light and Optics

• 1. Define WAVE - a moving disturbance that
  transfers energy from one place to
  another2. List and define the two types of
  waves. TRANSVERSE WAVE - particles of the medium
  vibrate perpendicular to the direction the wave
  is moving. LONGITUDINAL WAVE (COMPRESSIONAL
  WAVE) - particles of the medium vibrate parallel
  to the direction the wave is moving

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Waves, Sound, Light and Optics

• 3.Identify these terms as they apply to a
  transverse wave nodal line, crest, trough,
  amplitude and wavelength.
• NODAL LINE - the usual resting position of the
  wave
• CREST - uppermost point of a transverse wave
• TROUGH - lowest point of a transverse wave
• AMPLITUDE - the distance from the nodal line to
  the crest or nodal line to the trough
• WAVELENGTH - the distance between two identical
  successive points on a wave (crest to crest or
  trough to trough)

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Waves, Sound, Light and Optics

• 4. Identify these terms as they apply to a
  longitudinal wave compression, rarefaction and
  wavelength.
• COMPRESSION - area where the molecules are packed
  closely together
• RAREFACTION - area where the molecules are spread
  far apart
• WAVELENGTH - the distance between any two
  identical successive points on a wave
  (compression to compression, rarefaction to
  rarefaction)

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Waves, Sound, Light and Optics

• 5. Define frequency and Hertz.
• FREQUENCY - the number of waves that pass a given
  point in one second
• HERTZ - the unit for frequency waves per second
• 450 waves per second 450 Hz

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Waves, Sound, Light and Optics

• 6. Use the wave equation to solve for velocity,
  frequency or wavelength when two of the variables
  are known.
• VELOCITY FREQUENCY X WAVELENGTH
• v ??
• Velocity .......... meters per second (m/s)
• Frequency ƒ .... waves per second (Hz)
• Wavelength ?....... meters per wave (m)

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Waves, Sound, Light and Optics

• 7. List the three conditions necessary to have
  sound.
• In order to satisfy the scientific definition of
  sound, there must be a source, medium and
  receiver.
• SOURCE - something to vibrate and produce the
  sound wave
• MEDIUM - something for the sound wave to travel
  through
• RECEIVER - something to detect (hear) the sound
  wave

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Waves, Sound, Light and Optics

• 8. Relate the speed of sound to
• (a) density of the medium
• (b) temperature of the medium
• The more dense the medium, the faster sound
  travels. (solid, liquid, gas)
• The higher the temperature within a medium, the
  faster sound travels. (hot air, cold air)

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Waves, Sound, Light and Optics

• 9. State the speed of sound in English and
  metric units.
• The speed of sound can be expressed as
• 334 meters per second (m/s)
• 1090 feet per second (ft/s)
• 750 miles per hour (Mach 1)

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Waves, Sound, Light and Optics

• 10. Define echo and state the conditions
  necessary for a human to hear an echo.
• ECHO - reflected sound wave
• To hear an echo, the original sound and the
  returning sound must be at least 1/10 of a second
  apart.
• Usually, this means the reflecting surface must
  be at least 55 feet away for a human to hear the
  echo.

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Waves, Sound, Light and Optics

• 11. Explain how echoes are prevented in
  auditoriums.
• An echo is prevented by use of sound absorbing
  materials such as padded seats, curtains on the
  walls and carpeting.

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Waves, Sound, Light and Optics

• 12. Solve mathematical word problems involving
  ECHOES.
• Use the formula vd/t. If given the distance in
  an echo problem, this distance must be doubled in
  order to solve for time. If given the time in an
  echo problem, this time must be cut in half to
  solve for distance.
• source gtgtgtgtgtgtgtgtgt reflecting wall

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Waves, Sound, Light and Optics

• Source

Reflecting Wall
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Waves, Sound, Light and Optics

• 13. Distinguish between noise and musical tones.
• NOISE - a series of irregular vibrations if shown
  on the screen of an oscilloscope
• MUSIC - a series of regular or smooth patterns if
  shown on the screen of an oscilloscope

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Waves, Sound, Light and Optics

• 14. List the four types of musical instruments.
• The four types of musical instruments are wind,
  string, percussion and electronic.
• STRING INSTRUMENTS produce sounds by vibrating
  strings
• WIND INSTRUMENTS produce sounds by a vibrating
  column of air
• PERCUSSION INSTRUMENTS produce sound by a
  vibrating membrane
• ELECTRONIC INSTRUMENTS produce sound by use of
  electricity and computers

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Waves, Sound, Light and Optics

• 15. Discuss ways to vary the frequency of a
  vibrating object.
• To give a string instrument a high pitch, the
  string should be tight, short and thin.
• To give a string instrument a low pitch, the
  string should be long, loose and thick.
• Same principals apply to percussion and wind
  instruments in different applications.
• End of Material for Test 1

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Waves, Sound, Light and Optics

• 16. Describe the electromagnetic spectrum.
• The EM spectrum consists of light at all possible
  energies, frequencies and wavelengths.
• All waves of the EM spectrum travel at the same
  speed. (speed of light)
• All waves of the EM spectrum have different
  wavelengths and frequencies.
• The EM spectrum includes gamma rays, x-rays,
  ultraviolet, visible, infrared, microwaves and
  radiowaves in order of increasing wavelength and
  decreasing frequency. (short to long wavelength)

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Waves, Sound, Light and Optics

• Gamma rays
• highest energy and shortest wavelengths
• wavelengths less than 10-14m
• extreme high energy, can be dangerous and may
  kill living cells or turn them into cancer cells.
  
• used to treat cancer by killing the diseased
  cells
• controversy surrounds the use of gamma rays in
• the irradiation of food.

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Waves, Sound, Light and Optics

• X-rays
• wavelengths less than 10-8m
• commonly used in hospitals, most x-rays pass
  through the human body but bones and other
  tissues absorb a few.
• Sunlight contains ultraviolet (UV) waves.
• 9 of the energy emitted by the sun is UV light
• high energy, some UV light can pass through thin
  layers of clouds, causing you to sunburn on
  cloudy or overcast days

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Waves, Sound, Light and Optics

• Visible
• that portion of the EM spectrum humans can see
• commonly remembered as ROY G BIV
• red has the longest wavelength and lowest
  frequency (4.3 x 1014 Hz)
• violet has the shortest wavelength and highest
  frequency (7.5 x 1014 Hz).

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Waves, Sound, Light and Optics

• Infrared
• felt as warmth
• slightly longer than the color red, these waves
  warm you
• infrared lamps are used to keep food warm in a
  cafeteria or restaurant.

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Waves, Sound, Light and Optics

• Microwaves
• used in cooking and communication
• microwave ovens in the US use waves with a
  frequency of 2450 MHz (or wavelength of 12.2 cm)
• reflected by metals but are easily transmitted
  through air, glass, paper and plastic
• able to cook and heat food because water, fat
  and sugar absorb these waves and their energy
  microwaves can travel about 3-5 cm into the food
• microwaves are also used in telecommunication
  signals

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Waves, Sound, Light and Optics

• Radio waves
• are the longest waves of the EM spectrum
• ranges in length from tenths of a meter to
  millions of meters.
• includes TV signals, AM and FM radio signals
• radar, used by air traffic controllers and
  police are also examples of radio waves

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Waves, Sound, Light and Optics

• 17. List the three theories on the nature of
  light.
• (a) particle theory
• (b) wave theory
• (c) photon theory (a photon is a bundle of
  energy)
• Scientists do NOT know exactly how to describe
  light.

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Waves, Sound, Light and Optics

• 18. State the speed of light in a vacuum.
• 186,000 miles/second
• 3 x 108 m/s, or 3 x 1010 cm/s
• in a vacuum!
• Slower in gases, liquids and solids because the
  molecules of these substance slow it down. The
  denser the medium, the slower light travels.

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Waves, Sound, Light and Optics

• 19. Name in order, the colors of the visible
  spectrum.
• ROY G BIV - red, orange, yellow, green, blue,
  indigo, violet

Waves, Sound, Light and Optics
Red orange yellow green blue indigo violet
long ? low ? short ? high ?
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Waves, Sound, Light and Optics

• 20. Compare wavelength, frequency and energy for
  the waves of the visible spectrum.
• Red longest wavelength, lowest frequency
  lowest amount of energy
• Violet shortest wavelength, highest frequency,
  greatest amount of energy
• Waves of higher frequency contain more energy.

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Waves, Sound, Light and Optics

• 21. Define and indicate examples of transparent,
  translucent and opaque objects.
• transparent - allows most light to pass through-
  produces clear images. (clear smooth glass)
• translucent - allows some light to pass through-
  produces blurry images (wax paper, frosted glass,
  stained glass, etc....)
• opaque - blocks most light- produces no image
• 22. Define reflection.
• Reflection -the bouncing of a wave from a barrier.

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Waves, Sound, Light and Optics

• 23. Describe constructive interference and
  destructive interference of light waves.
• Constructive interference occurs when two waves
  line up so their crests overlap. They add
  together to make a larger wave.
• Destructive interference occurs when the crest of
  one wave overlaps the trough of another wave.
• Subtraction occurs to produce a smaller or
  non-existent wave. Colors seen on soap bubbles
  and oils spills are due to this interference.

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Waves, Sound, Light and Optics

• 24. Name the primary, secondary and
  complimentary colors of light.
• Primary colors of light
• red, blue, green
• (red blue green white light)
• Secondary colors
• cyan, magenta, yellow
• red blue magenta
• red green yellow
• blue green cyan

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Waves, Sound, Light and Optics

• Complimentary colors
• Refer to a pair of colors
• (one primary and one secondary)
• produce white light when combined
• magenta green white light
• yellow blue white light
• cyan red white light

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Waves, Sound, Light and Optics

• 25. Describe color addition and color
  subtraction.
• Color addition if the process of combining the
  additive primary colors (red, blue, green) to
  produce other colors.
• Color subtraction involves the absorption of
  colors to produce those that we see.
• White is not a color, but the presence of all
  colors. Black is not a color, but the absence of
  all colors.

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Waves, Sound, Light and Optics

• 26. Identify the colors used in color print
  advertisements.
• Print advertisements use the colors of yellow,
  cyan and magenta. A fourth "color", black is
  used for sharpness and contract.

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Waves, Sound, Light and Optics

• 27. Identify the colors associated with color
  blindness.
• color-blindness - a sex linked genetic trait
• people cannot see certain colors as others.
  Usually involves the colors red, green or both
• cone cells of the retina do not receive the
  color and pass it through the optic nerve to the
  brain as they should
• A totally color-blind person would see black and
  white and shades of gray (much like watching a
  black and white television).