© 2010 Pearson Education, Inc. Conceptual Physics 11 th Edition Chapter 26: PROPERTIES OF LIGHT

© 2010 Pearson Education, Inc. Chapter 26 Objectives Electromagnetic Waves The Electromagnetic Spectrum Transparent Materials Opaque Materials Warm-Up If I shake an electrically charged balloon will I create an electromagnetic wave?

© 2010 Pearson Education, Inc. Answer YES!! But… Light is the only thing we can see. Originates from the accelerated motion of electrons Electromagnetic phenomenon

© 2010 Pearson Education, Inc. Electromagnetic Waves Electromagnetic wave Made up of vibrating electric and magnetic fields- perpendicular to each other and direction of travel

© 2010 Pearson Education, Inc. If an electron vibrates up and down 1000 times each second, it generates an electromagnetic wave with a A.period of 1000 s. B.speed of 1000 m/s. C.wavelength of 1000 m. D.None of the above. Electromagnetic Waves CHECK YOUR NEIGHBOR

© 2010 Pearson Education, Inc. If an electron vibrates up and down 1000 times each second, it generates an electromagnetic wave with a A. period of 1000 s. B.speed of 1000 m/s. C.wavelength of 1000 m. D.None of the above. Explanation: The vibrating electron would emit a wave with a frequency of 1000 Hz, which is not in the list above. Electromagnetic Waves CHECK YOUR ANSWER *EM waves travel in free space *They don’t change speed (if they did then the decrease in electric field would produce a decrease in magnetic field which would decrease the electric field so on and so on….until it DIED)

© 2010 Pearson Education, Inc. Electromagnetic Spectrum

© 2010 Pearson Education, Inc. Electromagnetic Spectrum ARE radio waves and sound waves the same? Are they both on the EM spectrum?

© 2010 Pearson Education, Inc. Antennas Cell phones use VERY LONG (about 1000meters) wavelengths, old antennas needed the wavelength to be ¼ of a wavelength long, fractal (a shape that repeats itself) antennas allowed the size to decrease.

© 2010 Pearson Education, Inc. The electromagnetic spectrum spans waves ranging from lowest to highest frequencies. The smallest portion of the electromagnetic spectrum is that of A.radio waves. B.microwaves. C.visible light. D.gamma rays. Electromagnetic Spectrum CHECK YOUR NEIGHBOR

© 2010 Pearson Education, Inc. The electromagnetic spectrum spans waves ranging from lowest to highest frequencies. The smallest portion of the electromagnetic spectrum is that of A.radio waves. B.microwaves. C.visible light. D.gamma rays. Electromagnetic Spectrum CHECK YOUR ANSWER

© 2010 Pearson Education, Inc. Which of these is fundamentally different from the others? A.Sound waves B.Light waves C.Radio waves D.X-rays Electromagnetic Spectrum CHECK YOUR NEIGHBOR

© 2010 Pearson Education, Inc. Which of these is fundamentally different from the others? A.Sound waves B.Light waves C.Radio waves D.X-rays Explanation: All are electromagnetic waves except sound, which is a mechanical wave. Electromagnetic Spectrum CHECK YOUR ANSWER

© 2010 Pearson Education, Inc. Exit Ticket HW: DUE FRIDAY –Page 470 1, 2, 3, 11, 12, 16, 21, 26, 29, 32, 33, 34, 38

© 2010 Pearson Education, Inc. Chapter 26 Objectives Electromagnetic Waves The Electromagnetic Spectrum Transparent Materials Opaque Materials Warm-Up Can you get a sunburn on a cloudy day? Can you get a sunburn inside near a window?

© 2010 Pearson Education, Inc. Transparent Materials Light is transmitted similarly to sound. Both are vibrations due to a vibrating source. And they can transfer the vibration.

© 2010 Pearson Education, Inc. Transparent Materials- light enters and leaves in a straight line How light penetrates transparent material such as glass: Electrons or molecules in the glass are forced into vibration. Energy is momentarily absorbed and vibrates the electrons in the glass. This vibrating electron either emits a photon (a corpsucle of light) or transfers the energy as heat.

© 2010 Pearson Education, Inc. Transparent Materials Time delay between absorption and re-emission of energy of vibrating electrons results in a lower average speed of light through a transparent material. …..basically light travels at different speeds in different materials. –Fast in air, then liquid and slowest in glass

© 2010 Pearson Education, Inc. Transparent Materials In glass, infrared waves, with frequencies lower than those of visible light, cause not only the electrons but entire atoms or molecules to vibrate, increasing the temperature of the structure. So we see that glass is transparent to visible light, but not to ultraviolet and infrared light.

© 2010 Pearson Education, Inc. Strictly speaking, the photons of light incident on glass are A.also the ones that travel through and exit the other side. B.not the ones that travel through and exit the other side. C.absorbed and transformed to thermal energy. D.diffracted. Transparent Materials CHECK YOUR NEIGHBOR

© 2010 Pearson Education, Inc. Strictly speaking, the photons of light incident on glass are A.also the ones that travel through and exit the other side. B.not the ones that travel through and exit the other side. C.absorbed and transformed to thermal energy. D.diffracted. Explanation: Figure 26.7 illustrates this nicely. The light that exits the glass is not the same light that begins the process of absorption and re-emission. Transparent Materials CHECK YOUR ANSWER

© 2010 Pearson Education, Inc. Compared with the frequency of illuminating light on a sheet of transparent plastic, the frequency of light that is transmitted A.is slightly less. B.is the same. C.is slightly higher. D.depends on the type of plastic. Transparent Materials CHECK YOUR NEIGHBOR

© 2010 Pearson Education, Inc. Compared with the frequency of illuminating light on a sheet of transparent plastic, the frequency of light that is transmitted A.is slightly less. B.is the same. C.is slightly higher. D.depends on the type of plastic Explanation: Speed of light in plastic may vary, but the frequency transmitted doesn’t. Transparent Materials CHECK YOUR ANSWER

© 2010 Pearson Education, Inc. The average speed of light is less in A.air before entering glass. B.glass. C.air after emerging from glass. D.None of the above. Transparent Materials CHECK YOUR NEIGHBOR

© 2010 Pearson Education, Inc. The average speed of light is less in A.air before entering glass. B.glass. C.air after emerging from glass. D.None of the above. Transparent and Opaque Materials CHECK YOUR ANSWER

© 2010 Pearson Education, Inc. Opaque Materials Most things around us are opaque—they absorb light without re-emitting it. –Books, desks, chairs, and people are opaque. Vibrations given by light to their atoms and molecules are turned into random kinetic energy—into internal energy. –These materials become slightly warmer.

© 2010 Pearson Education, Inc. Opaque Materials Metals Light shining on metal forces free electrons in the metal into vibrations that emit their own light as reflection. This also makes them shiney.

© 2010 Pearson Education, Inc. Opaque Materials Light incident on dry surfaces bounces directly to your eye. wet surfaces bounces inside the transparent wet region, absorbing energy with each bounce, and reaches your eye darker than from a dry surface.

© 2010 Pearson Education, Inc. Exit Ticket Which situation will produce a better and sharper shadow: –An object close to the wall –An object far from the wall –You need your lab book for block day

© 2010 Pearson Education, Inc. Chapter 26 Objectives Electromagnetic Waves The Electromagnetic Spectrum Transparent Materials Opaque Materials Warm-Up LAB DAY

© 2010 Pearson Education, Inc. Opaque Materials Shadows A thin beam of light is often called a ray. When we stand in the sunlight, some of the light is stopped while other rays continue in a straight-line path. We cast a shadow—a region where light rays do not reach.

© 2010 Pearson Education, Inc. Opaque Materials Either a large, far-away light source or a small, nearby light source will produce a sharp shadow. A large, nearby light source produces a somewhat blurry shadow.

© 2010 Pearson Education, Inc. Opaque Materials There is usually a dark part on the inside and a lighter part around the edges of a shadow. A total shadow is called an umbra and A partial shadow is called a penumbra. –A penumbra appears where some of the light is blocked but where other light fills it in. –A penumbra also occurs where light from a broad source is only partially blocked.

© 2010 Pearson Education, Inc.

Opaque Materials In a solar eclipse, because of the large size of the Sun, the rays taper to provide an umbra (total eclipse) and a surrounding penumbra (partial eclipse). In a lunar eclipse, the Moon passes completely into the shadow of Earth.

© 2010 Pearson Education, Inc. Chapter 27 Objective Color in Our World Selective Reflection Selective Transmission Warm-Up “Roses are red, violets are blue, why is this true”?

© 2010 Pearson Education, Inc. Selective Reflection Each type of light will have a freq. so colors are more pronounced when viewed with different light (Incandescent vs fluorescent) Compare red vs blue wavelength and freq. Each color has a wavelength and freq. This freq. will cause the atoms (actually electrons) in the material to vibrate. The material has a natural freq. (the light is a forced vibration this increases amplitude due to resonance) that it absorbs …other freq. of light are reemitted. The ones reemitted are the color or colors that we see.

© 2010 Pearson Education, Inc. Remember the EM spectrum? What about white light? What about black? What does a prism do?

© 2010 Pearson Education, Inc. Selective Reflection Objects reflect light of some frequencies and absorb the rest. Rose petals absorb most of the light and reflect red. Objects that absorb light and reflect none appear black. Objects can reflect only those frequencies present in the illuminating light.

© 2010 Pearson Education, Inc.

Selective Transmission Color of transparent object depends on color of light it transmits. Colored glass is warmed due to the energy of absorbed light illuminating the glass.

© 2010 Pearson Education, Inc. Food for thought 1.If blue glass transmits blue light; then what color does white glass transmit? 2.If red light shines on a rose; what becomes warm…the rose or the leaves, why? 3.Why aren’t things just red or orange or just the colors on the VLS?

© 2010 Pearson Education, Inc. Exit Ticket HW: DUE FRIDAY page 484 1, 3, 6, Page , 39, 40, 41, 46, 47, 49

© 2010 Pearson Education, Inc. Beautiful World- Chapter 27 All the science that God knew but we had to figure out

© 2010 Pearson Education, Inc. Why is the Sky Blue?

© 2010 Pearson Education, Inc. Why is the Sky Blue? A tuning fork can have destructive interference= muffled scattered sound Ting tuning forks have high freq. and pitch Tiny particles (nitrogen and oxygen in our atmosphere) will scatter high freq. light like violet and blue Actually violet is scattered more but our eyes are not very sensitive to violet so we see blue Water vapor and smog change the color to deep blue or gray.

© 2010 Pearson Education, Inc. Why are Sunsets Red?

© 2010 Pearson Education, Inc. Why are Sunsets Red? Violet and blue are scattered so Red and orange are transmitted. At sunset violet and blue are scatters SO much that ROY are transmitted This is b/c the farther V and B travel the MORE scattered they are Sunlight travels through more atmosphere at sunset b/c it takes a longer path.

© 2010 Pearson Education, Inc.

Why are Clouds White

© 2010 Pearson Education, Inc. Why are Clouds White Small water droplets= scatter blue (also the high intensity of electrons vibrating = bright white) Medium sized= scatter green Large= scatter red= the low intensity of large droplets make them dark= rain When you add up all the colors=white

© 2010 Pearson Education, Inc. What is the “real” color of water

© 2010 Pearson Education, Inc. What is the “real” color of water Blue….no that’s just b/c it reflects the color of the sky Greenish-blue?! Yes, this is b/c red wavelengths can only penetrate water so far. When it can no longer penetrate (and is thus removed) you get red’s complementary color which is Greenish-blue Of course, run-off and particles in water change the color of water due to light scattering.

© 2010 Pearson Education, Inc.

Polarized Light

© 2010 Pearson Education, Inc. Chapter 28 Objective Reflection vs Refraction Principle of Least Time Rainbows Total Internal Reflection Lenses Warm-Up 1.What are the colors of the rainbow? 2.What does a prism do to light? 3.What color light does a prism use? 4.How does a rainbow “create” the colors you see? 5.What creates a mirage?

© 2010 Pearson Education, Inc. Rainbows Rainbows are a result of dispersion by many drops. Dispersion of light by a single drop

© 2010 Pearson Education, Inc. Rainbows Sunlight incident on two sample raindrops, as shown, emerges from them as dispersed light. The observer sees the red light from the upper drop and the violet light from the lower drop. Millions of drops produce the whole spectrum of visible light.

© 2010 Pearson Education, Inc. Light reflecting from a smooth surface undergoes a change in A.frequency. B.speed. C.wavelength. D.None of the above. Law of Reflection CHECK YOUR NEIGHBOR

© 2010 Pearson Education, Inc. Light reflecting from a smooth surface undergoes a change in A.frequency. B.speed. C.wavelength. D.None of the above. Law of Reflection CHECK YOUR ANSWER

© 2010 Pearson Education, Inc. Reflection We say light is reflected when it is returned into the medium from which it came—the process is reflection. When light illuminates a material, electrons in the atoms of the material move more energetically in response to the oscillating electric fields of the illuminating light. The energized electrons re-emit the light by which you see the material.

© 2010 Pearson Education, Inc. Principle of Least Time The idea that light takes the quickest path in going from one place to another is called Fermat’s principle of least time.

© 2010 Pearson Education, Inc. The law of reflection applies to A.light. B.sound. C.Both A and B. D.None of the above. Law of Reflection CHECK YOUR NEIGHBOR

© 2010 Pearson Education, Inc. The law of reflection applies to A.light. B.sound. C.Both A and B. D.None of the above. Law of Reflection CHECK YOUR ANSWER

© 2010 Pearson Education, Inc. Refraction When light bends in going obliquely from one medium to another, we call this process refraction.

© 2010 Pearson Education, Inc. Refraction Illusions caused by refraction Objects submerged in water appear closer to the surface.

© 2010 Pearson Education, Inc. Refraction Illusions caused by refraction (continued) Objects such as the Sun seen through air are displaced because of atmospheric refraction. The sun appears to be higher in the sky during a sunset because the top atm is thin and light travels faster there.

© 2010 Pearson Education, Inc. When light travels from one medium to another and changes speed in doing so, we call the process A.reflection. B.interference. C.dispersion. D.refraction. Refraction CHECK YOUR NEIGHBOR

© 2010 Pearson Education, Inc. When light travels from one medium to another and changes speed in doing so, we call the process A.reflection. B.interference. C.dispersion. D.refraction. Refraction CHECK YOUR ANSWER

© 2010 Pearson Education, Inc. Pit Stop Take notes from white board

© 2010 Pearson Education, Inc. Refracted light that bends toward the normal is light that has A.slowed down. B.sped up. C.nearly been absorbed. D.diffracted. Refraction CHECK YOUR NEIGHBOR

© 2010 Pearson Education, Inc. Refracted light that bends toward the normal is light that has A.slowed down. B.sped up. C.nearly been absorbed. D.diffracted. Refraction CHECK YOUR ANSWER

© 2010 Pearson Education, Inc. Refracted light that bends away from the normal is light that has A.slowed down. B.sped up. C.nearly been absorbed. D.diffracted. Refraction CHECK YOUR NEIGHBOR

© 2010 Pearson Education, Inc. Refracted light that bends away from the normal is light that has A.slowed down. B.sped up. C.nearly been absorbed. D.diffracted. Explanation: This question is a consistency check with the question that asks about light bending toward the normal when slowing. Refraction CHECK YOUR ANSWER

© 2010 Pearson Education, Inc. Exit Ticket HW: DUE FRIDAY –Pg 505 8, 10, 11 –Pg 507 8, 14 –Pg , 34 –Pg , 43, 45

© 2010 Pearson Education, Inc. Chapter 28 Objective Reflection vs Refraction Principle of Least Time Rainbows Total Internal Reflection Lenses Warm-Up 1.What is the warning on the side view mirrors on a car?

© 2010 Pearson Education, Inc. Atmospheric refraction occurs with changes in wind speed. air temperature. Either of these. None of these.

© 2010 Pearson Education, Inc. Atmospheric refraction occurs with changes in wind speed. air temperature. Either of these. None of these. Comment: Interestingly, sound refraction does depend on wind speeds.

© 2010 Pearson Education, Inc. Pit Stop Take notes from white board

© 2010 Pearson Education, Inc. Mirror, mirror on the wall…..

© 2010 Pearson Education, Inc. When light incident on a prism separates into a spectrum, we call the process reflection. interference. diffraction. None of these.

© 2010 Pearson Education, Inc. When light incident on a prism separates into a spectrum, we call the process reflection. interference. diffraction. None of these. Explanation: The process is called dispersion. See this illustrated in Figure

© 2010 Pearson Education, Inc. A rainbow is the result of light in raindrops that undergoes reflection. interference. diffraction. None of these.

© 2010 Pearson Education, Inc. A rainbow is the result of light in raindrops that undergoes reflection. interference. diffraction. None of these.

© 2010 Pearson Education, Inc. After lab activity DUE AT THE END OF THE PERIOD Write a children’s story OR a song OR Create a foldable Include: –The difference between real and virtual images –A sketch of a plane, concave and convex mirror –An explanation of what they do to an image –An explanation of the image produced, meaning is the image real or virtual.

© 2010 Pearson Education, Inc. Chapter 30 Objective Excitation Emission Spectra Incandescence Fluorescence Phosphorescence LED Lasers Warm-Up Which type of electron uses LESS energy to stay on the atom…the electron close to the nucleus or the electron far from the nucleus?

© 2010 Pearson Education, Inc. Excitation Electrons close=less energy Electron far= more energy Just as each element is characterized by the number of electrons that occupy the shells surrounding its atomic nucleus, each element also possesses its own characteristic pattern of electron shells, or energy states. When energy is imparted to an element, an electron may be boosted to a higher energy level. The atom is said to be excited. When the electron goes back to the lower energy level = de-excitation then light energy (photon) is released E=freq.

© 2010 Pearson Education, Inc. Excitation is the process in which A.electrons are boosted to higher energy levels in an atom. B.atoms are charged with light energy. C.atoms are made to shake, rattle, and roll. D.None of the above. Excitation CHECK YOUR NEIGHBOR

© 2010 Pearson Education, Inc. Excitation is the process in which A.electrons are boosted to higher energy levels in an atom. B.atoms are charged with light energy. C.atoms are made to shake, rattle, and roll. D.None of the above. Excitation CHECK YOUR ANSWER

© 2010 Pearson Education, Inc. Excitation- draw picture teacher draws on board Excitation The frequency of an emitted photon ~ energy- level difference in de-exciting: E = hf

© 2010 Pearson Education, Inc. Examples- how do I use this handout?! 1.n=6 to n= 2 what color and tell me about the freq, energy and wavelength 2.n=3 to n=2 what color and tell me about the freq, energy and wavelength 3.n=5 to n=2 4.n=4 to n=2 5.n=4 to n=1 6.n=2 to n=1 7.n=6 to n=3 8.n=4 to n=3

© 2010 Pearson Education, Inc. Which has less energy per photon? A.Red light B.Green light C.Blue light D.All have the same. Excitation CHECK YOUR NEIGHBOR

© 2010 Pearson Education, Inc. Which has less energy per photon? A.Red light B.Green light C.Blue light D.All have the same. Explanation: In accord with E ~ f, the lowest-frequency light has the lowest energy per photon. Excitation CHECK YOUR ANSWER

© 2010 Pearson Education, Inc. What does color allow us to do? This characteristic allows us to “graph” the emissions on the emission spectrum FYI incandescent bulbs have a continuous spectrum We can use this information to identify elements We run the element in a flame which excites the electrons in the atom When the electrons go back to their ground state (n=2) then it releases the characteristic color for that element EX: sodium releases yellow flame color

© 2010 Pearson Education, Inc. Emission Spectra Spectral lines Forms an image of the slit on the screen using a spectroscope Each component of color is focused at a definite position according to frequency.

© 2010 Pearson Education, Inc. Most of what we know about atoms is gained by investigating the A.masses of elements. B.electric charge of elements. C.periodic table of the elements. D.light they emit. Emission Spectra CHECK YOUR NEIGHBOR

© 2010 Pearson Education, Inc. Most of what we know about atoms is gained by investigating the A.masses of elements. B.electric charge of elements. C.periodic table of the elements. D.light they emit. Explanation: Light emitted by atoms, their atomic spectra, are considered to be the fingerprints of atoms. Emission Spectra CHECK YOUR ANSWER

© 2010 Pearson Education, Inc. Exit Ticket HW: DUE FRIDAY –Page 544 1, 2, 4, 5 –Page , 24, 25, 30, 32, 47

© 2010 Pearson Education, Inc. Chapter 30 Objective Excitation Emission Spectra Incandescence Fluorescence Phosphorescence LED Lasers Warm-Up Who “invented” the incandescent bulb? What was the original filament made of? What is the filament made of now?

© 2010 Pearson Education, Inc. Incandescent & Light Bulb bb Latin for “to grow hot” Continuous spectrum Light is produced as a result of high temperature Colors: –Red= toaster –Blue=stars –White=bulb

© 2010 Pearson Education, Inc. Which lamp is more efficient for emitting light? A.Incandescent lamp B.Fluorescent lamp C.Both the same for the same wattage D.None of the above. Incandescence CHECK YOUR NEIGHBOR

© 2010 Pearson Education, Inc. Which lamp is more efficient for emitting light? A.Incandescent lamp B.Fluorescent lamp C.Both the same for the same wattage D.None of the above. Incandescence CHECK YOUR ANSWER

© 2010 Pearson Education, Inc. Fluorescence UV has very LOW wavelength and very HIGH freq. and energy, so the high energy is used to excite the electrons to very high energy states When it de-excites it releases visible light with very LOW freq. It will “hop” down rather then “jump” all the way down like mentioned first (Bhor model)= GLOW!!

© 2010 Pearson Education, Inc. An atom that absorbs a photon can then emit one A.only at the same energy. B.of any energy depending on the situation. C.only at a higher energy. D.only at the same or lower energy. Fluorescence CHECK YOUR NEIGHBOR

© 2010 Pearson Education, Inc. An atom that absorbs a photon can then emit one A.only at the same energy. B.of any energy depending on the situation. C.only at a higher energy. D.only at the same or lower energy. **detergents that make clothes “whiter” actually use fluorescent dyes to make your clothes “glow” using UV from sun Fluorescence CHECK YOUR ANSWER

© 2010 Pearson Education, Inc. Padlet Time Create a Padlet with: –The definition –An explanation –A Picture For Incandescence and Fluorescence You can THE LINK it to yourself so that you can edit it.

© 2010 Pearson Education, Inc. Chapter 30 Objective Excitation Emission Spectra Incandescence Fluorescence Phosphorescence LED Lasers Warm-Up What does LED stand for…Look it up for those of you that will say “I don’t know”

© 2010 Pearson Education, Inc.

LED Light Emitting Diode Solar Cells= take light and convert to electricity Reverse solar cell (LED)= take electricity and convert to light…The diode that does this is an LED 1.Great! For compact spaces (like a flashlight) 2.Efficient 3.No filament needed 4.Last 100X longer…WOW 5.No Mercury (Hg) needed…

© 2010 Pearson Education, Inc. Halloween We often see glow in the dark decorations during Halloween, but how do they REALLY work?

© 2010 Pearson Education, Inc. Phosphorescence Glow in dark stuff The atom stays excited for a long period of time emitting light for a long period of time Things that glow indefinitely have a radioactive material providing the energy to stay excited Animals have this too!! It’s called bioluminescence…and some fish only glow if they swim, if they don’t then they are too dark to see.

© 2010 Pearson Education, Inc.

Padlet Time Create a Padlet with: –The definition –An explanation –A Picture For LED and Phosphorescence You can THE LINK it to yourself so that you can edit it.

© 2010 Pearson Education, Inc. Chapter 30 Objective Excitation Emission Spectra Incandescence Fluorescence Phosphorescence LED Lasers Warm-Up What does laser stand for….yes look it up.

© 2010 Pearson Education, Inc. Lasers Light Amplification by Stimulated Emission of Radiation…WOW that is a long name

© 2010 Pearson Education, Inc. How it works Regular light from a lamp is “incoherent” meaning photons (or colors) of all frequency and wavelength are emitted (chaotic) this is why it is white. We can “filter” it so only red comes out but the waves are out of phase (destructive interference) To have a laser it must be coherent, in phase and the same color

© 2010 Pearson Education, Inc. Lasers Incoherent light (many frequencies and out of phase)

© 2010 Pearson Education, Inc. Lasers Lasers (continued) Monochromatic light out of phase

© 2010 Pearson Education, Inc. Lasers Lasers (continued) Coherent light of identical frequencies in phase

© 2010 Pearson Education, Inc. Lasers Lasers (continued) A device that produces a beam of coherent light Many types and many ranges of light (IR, VL, UV an used in surgery and welding Not a source of energy (as is sometimes thought)

© 2010 Pearson Education, Inc. How it works cont. An external energy source hits an active medium (wh. can be a s, l, g) It will excite the medium to a higher energy state and when it de-excites….It will create a chain rxn so other atoms also de-excite All the wavelengths hit a mirror wh. Is coated to absorb all wavelengths and reflect the desired one.

© 2010 Pearson Education, Inc.

Padlet Time Create a Padlet with: –The definition –An explanation –A Picture For Laser NO MORE THIS….. You can THE LINK it to yourself so that you can edit it. Now you must the Padlet to me. It must be complete with ALL of the definitions