IPC Waves, Sound, Light and Optics C. Smith. Waves, Sound, Light and Optics 1.Define WAVE - a moving disturbance that transfers energy from one place

IPC Waves, Sound, Light and Optics

C. Smith

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


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 waveCREST - uppermost point of a transverse waveTROUGH - lowest point of a transverse waveAMPLITUDE - the distance from the nodal line to the crest or nodal line to the troughWAVELENGTH - the distance between two identical successive points on a wave (crest to crest or trough to trough)


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


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


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 λ....... meters per wave (m)


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 waveMEDIUM - something for the sound wave to travel throughRECEIVER - something to detect (hear) the sound wave


8. Relate the speed of sound to:(a) density of the medium (b) temperature of the mediumThe 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)


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)


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.


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.


12. Solve mathematical word problems involving ECHOES.Use the formula v=d/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 >>>>>>>>> reflecting wall


Source

Reflecting Wall


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


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 stringsWIND INSTRUMENTS produce sounds by a vibrating column of airPERCUSSION INSTRUMENTS produce sound by a vibrating membraneELECTRONIC INSTRUMENTS produce sound by use of electricity and computers


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


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)


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.


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


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).


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.


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


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


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.


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.


19. Name in order, the colors of the visible spectrum.

ROY G BIV - red, orange, yellow, green, blue, indigo, violet

Red orange yellow green blue indigo violet

long low

short high



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


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 image22. Define reflection.Reflection -the bouncing of a wave from a barrier.


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.


24. Name the primary, secondary and complimentary colors of light.Primary colors of lightred, blue, green(red + blue + green = white light)Secondary colorscyan, magenta, yellow

red + blue = magentared + green = yellow

blue + green = cyan


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


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.


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.


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 bothcone 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).

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IPC Waves, Sound, Light and Optics C. Smith. Waves, Sound, Light and Optics 1.Define WAVE - a moving disturbance that transfers energy from one place