Waves, Sound, and Light
Chapter 3
Bell Work 11/20/09
1.How long did you study for yesterday’stest?
2.How do you think you did on the test?
3.Will you do anything different next time?Why or why not? (at least 2 sentences)
Bell Work 11/23/09
1.What is the electromagnetic spectrum?
State whether each statement is true orfalse. If false make the statement true.
2. Mechanical waves transfer energy througha vacuum.
3. A wave is a disturbance that transfersenergy.
4. Most EM waves are invisible butdetectable.
Bell Work 11/24/09
Please begin workingon yourelectromagneticposter.
Bell work 11/25/09
1.List the colors of the visible lightspectrum in order from longestwavelength to shortest wavelength.
2.What are the 7 parts of theelectromagnetic spectrum?
Bell Work 11/30/09
Please use complete sentences
1.Give an example of using a radio wave.
2.Give an example of using a microwave.
3.Give an example of using an x-ray.
1.1 Vocab
Electromagnetic wave – a disturbance thattransfers energy through a field
Radiation – energy that moves in the formof EM waves
How EM waves form and sourcesof EM waves
•Electric and magnetic fields make up EMwaves
•Many of the EM waves on Earth’senvironment come from the Sun.
•Stars give off EM waves but since they areso far away not many of their waves hit theEarth
•Technology is also a source of EM waves
Bell Work 12/1/09
1.What do electromagnetic wavestransfer energy through?
2.What is radiation?
3.How does a microwave cookfood?
Electromagnetic spectrum
•The range of all EM frequencies
•The spectrum goes from the lowestfrequencies to the highestfrequencies
•Higher-frequency EM waves withmore electromagnetic vibrations persecond have more energy than lower-frequency EM waves
Measuring EM Waves
•EM wave frequency ismeasured in hertz (Hz)
•One hertz equals one cycleper second
Radio waves
•Have the longest wavelengths, the lowestfrequencies, and the lowest energies
•Examples of radio waves are AM/FM radioand broadcast television
Microwaves
•EM waves with shorter wavelengths, higherfrequencies, and higher energy than otherradio waves
•Radar – radio detection and ranging. Used tocontrol air traffic at airports, analyze weatherconditions and measure the speed of amoving vehicle
•Radar led to the invention of microwaveovens
•Cell phones – radio transmitter and receiverthat uses microwaves
Visible Light
•The part of the EM spectrum that humaneyes can see.
•Longest wavelengths are red all the way toviolet
•ROY G BIV
•Red, Orange, Yellow, Green, Blue, Indigo,Violet
Bell Work 12/2/09
1.What are EM waves measured in?
2.Give two examples of using a radio wave.
3.Give 3 examples of using a microwave.
4.List the colors of visible light from longestwavelength to shortest wavelength.
Infrared Light
•Type of EM wave most often associatedwith heat
•Sometimes referred to as heat rays
•You can feel it as warmth coming from thesun, a fire, or a radiator
•Infrared lamps are used to provide warmthin bathrooms and to keep food warm afterits been cooked
•Some animals can see in infrared light
Ultraviolet Light
•Has more energy than visible light
•The waves in this range can damage your skin andeyes
•Sun block and UV-protection sunglasses aredesigned to filter out the higher frequencies
•UV light can be used to sterilize medical instrumentsand food by killing harmful bacteria
•IV light causes skin cells to produce vitamin D whichis essential to good health
•UV light is visible to some animals. Bees and someother insects
X-rays
•Has a very high frequency and energy
•Pass easily through soft tissues of thebody, but are absorbed by the bone
•The x-rays pass through exposing the filmwhere there is no bone
•When getting x-rays other parts of thebody are covered with a lead vest to blockthe x-rays
Gamma rays
•Highest frequencies and energies of anyEM waves
•Produced by some radioactive substancesas well as the sun and other stars
•Gamma rays can penetrate the soft and thehard tissues of the body, killing normal cellsand causing cancer cells to develop
•Gamma rays can also be used to killcancer cells and fight tumors
Bell Work 12/3/09
1.Which group from the EM spectrum hasthe highest frequencies?
2.Which group pass easily through softtissues of the body, but are absorbedby the bone?
3.What can you use to filter out the highfrequencies of UV rays?
4.Which EM wave is most associated withheat?
Bell Work 12/4/09
Predict what would happen ifyou kept a green plant in thedark for one month. Explainwhy. (at least 3 sentences)
Vocab 3.3
Incandescence – the production oflight by materials at hightemperatures
Luminescence – the production oflight without the high temperature.Many organisms produce their ownvisible light through this.
Bioluminescence – production oflight by living organism. Theseorganism produce light fromchemical reactions rather thanintense heat.
Fluorescence – occurs when amaterial absorbs EM radiation ofone wavelength and gives off EMradiation of another.
Bell Work 12/5/09
1.What happened to the speed of EMwaves in a vacuum?
2.What happens when microwavesencounter water?
3.What produces the most EM waves onEarth?
Light 3.4 Notes
Transmission – the passage of anEM wave through a medium.
•If the light reflected from objectsdid not pass through the air,windows, or most of the eye, wecould not see the objects
Absorption – thedisappearance of an EMwave into the medium
•Absorption affects how thingslook, because it limits the lightavailable to be reflected ortransmitted
How Materials Transmit Light
•Transparent materials allow most ofthe light that strikes them to passthrough.
•Translucent materials transmit somelight, but they also cause it to spreadout in all directions.
•Opaque materials do not allow anylight to pass through them, becausethey reflect light, absorb light, or both
Scattering – the spreading out of light raysin all directions, because particles reflectand absorb the light
•Fog or dust in the air, mud in water, andscratches or smudges on glass can allcause scattering
•Scattering creates a glare and makes ithard to see even through a transparentmaterial
Polarization – a quality of light in whichall of its waves vibrate in the samedirection
•Polarizing filters reduce glare and makeit easier to see objects
Prism – a tool that uses refraction tospread out the different wavelengthsthat make up white light
•Prisms split light into colors by refractingwavelengths in different amounts
Color Reflection and Absorption
The color of an object or material isdetermined by two factors
1.the wavelengths it absorbs andthose it reflects
2.The wavelengths present in the lightthat shines on the object
•A material that reflects all wavelengthsof visible light appears white
•A material that absorbs allwavelengths of visible like appearsblack
•A green lime absorbs mostwavelengths but reflects green, so thelime looks green
Primary Colors of Light
•The human eye can detect only 3color bands: red, green, and blue
•Your brain perceives these threecolors and various mixtures of themas all the colors
Primary colors – red, green, and blue– can be mixed to produce all thepossible colors
Primary Pigments
•Materials can be mixed to producecolors just as light can
•Materials that are used to producecolors are called pigments
Primary pigments – cyan, yellow, andmagenta