Chapter 27 and 28

 Both a wave and a particle  Electromagnetic wave  Photon  Wave/Particle Duality (Quantum Physics)  Speed of Light (c) =  300,000,000 m/s (186,000 mph)  Light-year =  Distance light travels in one year  Light is created by vibrating electrons (charges)

 Broken into Electromagnetic Spectrum

 Transparent: light passes through (waves re-emmited)  Opaque: light does not pass through (waves absorbed)  Different materials = slower speed of light  Materials can be transparent to some frequencies of light and opaque to others  Glass: Visible Light = transparent Infrared/Ultraviolet = opaque (not transparent)

 Ray: a beam of light  Light is considered a bundle of rays  Shadow: when an object blocks some rays  Umbra: total shadow  Penumbra: partial shadow (some light from reflections or alternate source fills in the shadow)

 Light = transverse waves  Wave is oriented by how electron vibrates  Orientation of wave = polarization  Most sources are not polarized (all different angles)

 Polarization filters block all light not same angle as filter  Glare (reflection) from horizontal surfaces tends to polarize that way Vertical filter would block it  3-D viewing (each eye has different polarization filters)

 White light = all colors  Red  Orange  Yellow  Green  Blue  Indigo  Violet  Black = absence of light

 We see the color reflected by an object  Other colors are absorbed  Color of light can influence color seen (by lack of certain colors)

 Color transparent materials are opaque to all colors but the color they seem  For example: blue glass lets blue light through but absorbs all other colors

 Mostly white: but stronger in the yellow/green areas and weaker on the ends  This makes natural sunlight yellowish

 Red Light + Green Light + Blue Light = White Light  Red + Blue = Magenta  Blue + Green = Cyan  Red + Green = Yellow  Magenta + Cyan + Yellow = White  Any color can be made by mixing these three colors at different brightness  Complementary mixed = white

 Pigments mix to black  Pigment is color of light (or mix) that is reflected  Blue reflects Green/Blue/Violet (absorbs the rest)  Yellow reflects Red/Orange/Yellow/ Green (absorbs the rest)  Green reflects just Green (only color both yellow and blue reflect)

 Sky Blue?  Atmosphere acts like a prism and scatter the sunlight, Blue scatters the most so that is what we see  Sunsets Red?  Thicker atmosphere scatters light more, red gets scattered most  Water Greenish-Blue?  Water absorbs colors as it gets deeper Red/orange/yellow absorb at shallow water Green/blue/indigo/violet absorb at deeper levels

 Every element gives off specific colors when heated  Spectroscopes analyze the exact colors to identify exact elements