Electromagnetic Spectrum Low Frequencies High Frequencies Radio Waves 0 2 billion Hertz Communication carry information Change size of wave Amplitude Modulation A M Penetrate Change frequency of wave Frequency Modulation F M Microwaves 2 billion 100 billion Hertz Penetrate Heat 100 billion 10 trillion Hertz Sun s immediate warmth Cook foods Infrared 10 trillion 400 trillion Hertz Warm foods Sunburn Body radiates infrared Visible Light 400 750 trillion Hertz ROY G BIV Ultraviolet 750 trillion 100 000 trillion Damage or destroy cells Suntan Atmosphere absorbs 98 of U V Depletion of ozone O3 layer X rays 100 000 trillion 10 000 000 trillion Discovered by Roentgen 1895 Thought of as rays not waves Rays penetrate like bullets Gamma Rays 10 000 000 trillion Highest frequency wave Created in Deep Space Colliding Galaxies Above Gamma Matter Low frequency long wavelength High frequency tight wavelength All EM waves travel at same speed 186 282 miles sec Difference is how many crests pass a point in a second frequency The greater a wave s frequency the greater its energy Planck Wave Phenomena 1 Luminosity The process where an electromagnetic wave light wave is produced There are four ways to cause luminosity Heat an object Pass electricity through a gas Chemical reaction Nuclear reaction Coherent Light All the light waves are in phase with each other An analogy would be 100 soldiers marching in step LASER Light Amplification by the Stimulated Emission of Radiation A device which produces coherent light Uses of the LASER Medical applications Construction Entertainment CD player Hologram Refraction Normal Line Rule Diffraction The bending of waves as they travel from a medium of one density through a medium of another at other than right angles Any line drawn perpendicular to a surface If the beam of light goes from a medium of lower density Ex Air to a medium of higher density Ex Glass the beam bends toward the normal If it goes from higher to lower density it bends away from the normal The greater the frequency the greater the bend Bending of waves as they pass around the corner or edge of an object Polarization 3D Effects Current Future Interference The lower the frequency the greater the bend Pinhole Spectrum Creates a rainbow The process where all the waves are vibrating in the same direction Polarized sunglasses Reflected light is polarized Uses polarization depth perception front to back Uses holograms true 3D produced by lasers Depth perception Parallax side to side When two waves meet and form a new wave Constructive Interference When two crests meet and form a large wave Destructive Interference When a wave crest and trough meet and cancel each other Wave Phenomena 12 Theory expected Electron should vibrate in place Experiment what they saw Electron was ejected from atom Created free Photoelectric effect 1905 Electricity from light Problem Light behaving like a article of matter not a wave light was exerting a electrons electricity Solar panels Elevator doors force Flashlight beam Comet tails Einstein said Light can be both a wave and a particle Particle nature of light he called a Photon bundle or packet of energy Received his one only Nobel Prize 1921 for this Two Differences Between Orbiting Electrons and Planets May have more than one electron per shell No electron may orbit between shells forbidden zone In order for an electron to move outward from one shell to another a photon light In order for an electron to move inward from one shell to another a photon must be wave must be absorbed emitted produced created Octet Rule The farther an electron drops inward the greater the energy emitted Atoms like eight electrons in their outermost shell No matter what direction you observe light the speed of light remains 186 282 mi sec Einstein s Special Theory of Relativity Objects get smaller Mass increases Time slows down Nuclear Physics Fission Breakup of more complex elements Ex Nuclear decay Atom Bomb Nuclear Power Plant Fusion Combining of lighter elements to make heavier ones When atoms are fused there is a slight loss of mass