2000 Microsoft Clip Gallery WAVES SOUND LIGHT Waves

© 2000 Microsoft Clip Gallery WAVES: SOUND & LIGHT Waves carry energy from one place to another Visit www. worldofteaching. com For 100’s of free powerpoints

NATURE OF WAVES © 2000 Microsoft Clip Gallery n Waves (Def. ) – A wave is a disturbance that transfers energy. n Medium – Substance or region through which a wave is transmitted. n Speed of Waves – Depends on the properties of the medium.

SAMPLE LESSON: Light & the Electromagnetic Spectrum By D. L. Power Revised 1/20/01 © 2000 Microsoft Clip Gallery

Albert Einstein

LIGHT: What Is It? © 2000 Microsoft Clip Gallery Light Energy n Atoms n. As atoms absorb energy, electrons jump out to a higher energy level. n. Electrons release light when falling down to the lower energy level. n Photons - bundles/packets of energy released when the electrons fall. n Light: Stream of Photons n © 2000 Microsoft Clip Gallery

Electromagnetic Waves n Speed in Vacuum n 300, 000 km/sec n 186, 000 mi/sec © 2000 Microsoft Clip Gallery n Speed in Other Materials n Slower in Air, Water, Glass

Transverse Waves © 2000 Microsoft Clip Gallery n Energy is perpendicular to direction of motion n Moving photon creates electric & magnetic field n Light has BOTH Electric & Magnetic fields at right angles!

Electromagnetic Spectrum © 2000 Microsoft Clip Gallery

Electromagnetic Spectrum n Visible Spectrum – Light we can see n Roy G. Biv – Acronym for Red, Orange, Yellow, Green, Blue, Indigo, & Violet. n Largest to Smallest Wavelength.

Electromagnetic Spectrum n Invisible Spectrum n Radio Waves n. Def. – Longest wavelength & lowest frequency. n. Uses – Radio & T. V. broadcasting. © 2000 Microsoft Clip Gallery

Modulating Radio Waves © 2000 Microsoft Clip Gallery n Modulation - variation of amplitude or frequency when waves are broadcast n AM – amplitude modulation n Carries audio for T. V. Broadcasts n. Longer wavelength so can bend around hills n FM – frequency modulation n. Carries video for T. V. Broadcasts

Short Wavelength Microwave n Invisible Spectrum (Cont. ) n Infrared Rays n. Def – Light rays with longer wavelength than red light. n. Uses: Cooking, Medicine, T. V. remote controls

Electromagnetic Spectrum n Invisible spectrum (cont. ). n Ultraviolet rays. n. Def. – EM waves with frequencies slightly higher than visible light n. Uses: food processing & hospitals to kill germs’ cells n. Helps your body use vitamin D.

Electromagnetic Spectrum n Invisible Spectrum (Cont. ) n X-Rays n Def. - EM waves that are shorter than UV rays. n Uses: Medicine – Bones absorb xrays; soft tissue does not. n Lead absorbs X-rays.

Electromagnetic Spectrum n Invisible spectrum (cont. ) n Gamma rays n. Def. Highest frequency EM waves; Shortest wavelength. They come from outer space. n. Uses: cancer treatment.

LIGHT: Particles or Waves? n Wave Model of Light n Explains most properties of light n Particle Theory of Light n Photoelectric Effect – Photons of light produce free electrons © 2000 Microsoft Clip Gallery

LIGHT: Refraction of Light n Refraction – Bending of light due to a change in speed. n Index of Refraction – Amount by which a material refracts light. n Prisms – Glass that bends light. Different frequencies are bent different amounts & light is broken out into different colors.

Refraction (Cont. )

Refraction-Spectroscope Lab Hey girls! The filters go on the Spectroscope, not on the lashes! © 2000 D. L. Power

Color of Light Transparent Objects: n Light transmitted because of no scattering n Color transmitted is color you see. All other colors are absorbed. n Translucent: n Light is scattered and transmitted some. n Opaque: n Light is either reflected or absorbed. n Color of opaque objects is color it reflects. n © 2000 Microsoft Clip Gallery

Color of Light (Cont. ) n Color of Objects n White light is the presence of ALL the colors of the visible spectrum. n Black objects absorb ALL the colors and no light is reflected back. © 2000 Microsoft Clip Gallery

Color of Light (Cont. ) © 2000 Microsoft Clip Gallery Primary Colors of Light n Three colors that can be mixed to produce any other colored light n Red + blue + green = white light n Complimentary Colors of Light n Two complimentary colors combine to make white light-Magenta, Cyan, Yellow n

How You See © 2000 Microsoft Clip Gallery Retina – n Lens refracts light to converge on the retina. Nerves transmit the image n Rods – n Nerve cells in the retina. Very sensitive to light & dark n Cones – n Nerve cells help to see light/color n

Paint Pigments © 2000 Microsoft Clip Gallery n Pigments absorb the frequency of light that you see n Primary pigments n. Yellow + cyan + magenta = black n. Primary pigments are compliments of the primary colors of light.

Complementary Pigments © 2000 Microsoft Clip Gallery n Green, blue, red n Complimentary pigments are primary colors for light! © 2000 Microsoft Clip Gallery

LIGHT & ITS USES © 2000 Microsoft Clip Gallery n Sources of Light n Incandescent light – light produced by heating an object until it glows. © 2000 Microsoft Clip Gallery

LIGHT & ITS USES © 2000 Microsoft Clip Gallery n Fluorescent Light – n Light produced by electron bombardment of gas molecules n Phosphors absorb photons that are created when mercury gas gets zapped with electrons. The phosphors glow & produce light.

LIGHT & ITS USES - Neon n Neon light – neon inside glass tubes makes red light. Other gases make other colors. © 2000 Microsoft Clip Gallery

LIGHT & ITS USES - Reflection n Reflection – Bouncing back of light waves n Regular reflection – mirrors smooth surfaces scatter light very little. Images are clear & exact. n Diffuse reflection – reflected light is scattered due to an irregular surface.

LIGHT & ITS USES: Reflection Vocabulary n Enlarged – © 2000 Microsoft Clip Gallery n Image is larger than actual object. n Reduced – n Image is smaller than object. © 2000 Microsoft Clip Gallery

LIGHT & ITS USES: Reflection Vocabulary © 2000 Microsoft Clip Gallery n Erect – n Image is right side up. n Inverted – n Image is upside down. © 2000 Microsoft Clip Gallery

LIGHT & ITS USES: Reflection Vocabulary n Real Image – n Image is made from “real” light rays that converge at a real focal point so the image is REAL n Can be projected onto a screen because light actually passes through the point where the image appears n Always inverted

LIGHT & ITS USES: Reflection Vocabulary n Virtual Image– n “Not Real” because it cannot be projected n Image only seems to be there!

Light & Its Uses: Mirrors n Reflection Vocabulary © 2000 Microsoft Clip Gallery n Optical Axis – Base line through the center of a mirror or lens n Focal Point – Point where reflected or refracted rays meet & image is formed n Focal Length – Distance between center of mirror/lens and focal point

LIGHT & ITS USES: Mirrors n Plane Mirrors – Perfectly flat n Virtual – Image is “Not Real” because it cannot be projected n Erect – Image is right side up © 2000 Microsoft Clip Gallery

LIGHT & ITS USES: Mirrors n Reflection & Mirrors (Cont. ) n Convex Mirror n. Curves outward n. Enlarges images. n Use: Rear view mirrors, store security… CAUTION! Objects are closer than they appear! © 2000 Microsoft Clip Gallery

LIGHT & ITS USES: Lenses n Convex Lenses n Thicker in the center than edges. n Lens that converges (brings together) light rays. n Forms real images and virtual images depending on position of the object

LIGHT & ITS USES: Lenses n Convex Lenses n Ray Tracing Focal Point Object © 2000 D. L. Power Lens n Two rays usually define an image n. Ray #1: Light ray comes from top of object; travels parallel to optic axis; bends thru focal point.

LIGHT & ITS USES: Lenses Ray #1 n Convex Lenses n Ray Tracing © 2000 D. L. Power n Two rays define an image Ray #2 n. Ray 2: Light ray comes from top of object & travels through center of lens.

LIGHT & ITS USES: Lenses © 2000 D. L. Power n Concave Lenses – n Lens that is thicker at the edges and thinner in the center. n Diverges light rays n All images are erect and reduced.

How You See Near Sighted – Eyeball is too long and image focuses in front of the retina n Far Sighted – Eyeball is too short so image is focused behind the retina. n © 2000 Microsoft Clip Gallery

LIGHT & USES: Lenses n Concave Lenses – n Vision – Eye is a convex lens. n. Nearsightedness – Concave lenses expand focal lengths n. Farsightedness – Convex lenses shortens the focal length.

LIGHT & USES: Optical Instruments n Cameras n Telescopes n Microscopes © 2000 Microsoft Clip Gallery

LIGHT & USES: Optical Instruments n LASERS n Acronym: Light Amplification by Stimulated Emission of Radiation n Coherent Light – Waves are in phase so it is VERY powerful & VERY intense.

LIGHT & USES: Optical Instruments n LASERS n Holography – Use of Lasers to create 3 -D images n Fiber Optics – Light energy transferred through long, flexible fibers of glass/plastic n Uses – Communications, medicine, t. v. transmission, data processing.

LIGHT & USES: Diffraction – Bending of waves around the edge of a barrier. New waves are formed from the original. breaks images into bands of light & dark and colors. n Refraction – Bending of waves due to a change in speed through an object. n

LIGHT & USES: Diffraction © 2000 Microsoft Encarta n A diffraction grating. Each space between the ruled grooves acts as a slit. The light bends around the edges and gets refracted.

SAMPLE STUDENT PROJECT: Diffraction Grating Glasses (Pd. 1) © 2000 D. L. Power

SAMPLE STUDENT PROJECT: Diffraction Grating Glasses (Pd. 3)

SAMPLE STUDENT PROJECT: Diffraction Grating Glasses (Pd. 3) Hey girls, © 2000 D. L. Power are you hard at work or hardly working?

SAMPLE STUDENT PROJECT: Diffraction Grating Glasses (Pd. 5) Note: There’s more posing than working! © 2000 D. L. Power

SAMPLE STUDENT PROJECT: Diffraction Grating Glasses (Pd. 5) © 2000 D. L. Power

SAMPLE STUDENT PROJECT: Diffraction Grating Glasses (Pd. 5) © 2000 D. L. Power

SAMPLE STUDENT PROJECT: Diffraction Grating Glasses (Pd. 6) © 2000 D. L. Power

SAMPLE STUDENT PROJECT: Diffraction Grating Glasses (Pd. 6) © 2000 D. L. Power

EVALUATION: State Standards Waves carry energy from one place to another n Identify transverse and longitudinal waves in mechanical media such as spring, ropes, and the earth (seismic waves) n Solve problems involving wavelength, frequency, & speed. . n

EVALUATION: State Standards Radio waves, light, and x-rays are different wavelength bands in the spectrum of electromagnetic waves whose speed in vacuum is approximately 3 x 10 m/sec n Sound is a longitudinal wave whose speed depends on the properties of the medium in which it propagates. n

EVALUATION: State Standards n Identify the characteristic properties of waves: n Interference n Diffraction n Refraction n Doppler Effect n Polarization.

References http: //www. scimedia. com/chem-ed/light/em-spec. htm, updated 2/1/97 http: //encarta. msn. com/find/Concise. asp? ti=06 AFC 000 http: //www. lbl. gov/Micro. Worlds/ALSTool/EMSpec 2. html http: //www. lbl. gov/Micro. Worlds/ALSTool/EMSpec. html http: //www. physics. sfasu. edu/astro/color. html#linkshttp: //www. physics. sfasu. edu/ast ro/color. html#links http: //www. isc. tamu. edu/~astro/color. html

References http: //www. isc. tamu. edu/~astro/color. html http: //www. holo. com/holo/cmpany/laserart. htmlhttp: //www. holo. com /holo/cmpany/laserart. html http: //www. holo. com/holo/book 1. html#defhttp: //www. holo. co m/holo/book 1. html#def http: //www. scimedia. com/chem-ed/light/em-rad. htm, updated 11/22/97

WORKS CITED n http: //www. scimedia. com/chem-ed/light/em-rad. htm, updated 11/22/97 n http: //www. scimedia. com/chem-ed/light/em-spec. htm, updated 2/1/97 n http: //encarta. msn. com/find/Concise. asp? ti=06 AFC 000 n http: //www. lbl. gov/Micro. Worlds/ALSTool/EMSpec 2. html http: //www. lbl. gov/Micro. Worlds/ALSTool/EMSpec. html http: //www. physics. sfasu. edu/astro/color. html#links http: //www. isc. tamu. edu/~astro/color. html http: //www. holo. com/holo/cmpany/laserart. html http: //www. holo. com/holo/book/book 1. html#def n n n n

The End… © 2000 Microsoft Clip Gallery