Patterns of Light Chasing the Spectrum from Aristotle to LEDs

Light is all around us. Vision is our dominant sense, and we are richly rewarded with a palette of colors from red to violet. Our eyes do not detect the l- energy, long-wavelength infrared (IR) radiation, but we know it exists from d- cussions of war applications and televised images of guided weapons targets. Our eyes do not detect the higher-energy (above visible light energies) and shorter-than-visible-wavelength ultraviolet radiation, and yet we know it is there from the sunburn we receive in Arizona. We also know that window glass can block ultraviolet rays so we don’t get a burn while driving with the windows rolled up. We know about radio waves from the little boxes that talk to us and x-rays from the dentist office. These waves and rays belong to the same family of light, often called photons (from the Greek photos, light), that describes the spectra of electromagnetic radiation over 10 orders of magnitude from very low-energy - dio waves to very high-energy x-rays and gamma rays.

Introduction.- The Path of Light: Light beams, Light paths, Pinholes.- Reflection of Light: Mirrors, Daguerreotypes, Equal angles, Windows.- Refraction of Light: Speed of light, Waves, Refractive Index, Total internal reflection, Mirages.- Lenses: Focal length, Magnification, Photography, Fresnel lenses.- Color: Color and Light, The Eye and Color Sensation, Sources of Light, Composition of Light.- Rainbows: Your own rainbow, Secondary rainbows, Light inside, Double rainbows.- Blue skies and White clouds: Scattering, Rock candy/glass, Salt/sugar/foam, Water/ice.- Interference & Color: Soap bubbles, Oil/gas on water, Feathers.- Polarized light: Sunglasses, Blue sky.- The photon: a. Photoelectric effect, Solar panels, CCDs, LEDs.- Optical Spectroscopy: a. Light and electrons, Optical light emission, Prisms/gratings, Neon lights.- Electrons in atoms: Photons and electrons, X-rays, Optical absorption.- IR-UV-X-rays: Paintings in IR/UV/X-ray, Scorpions in UV, Suntans, Teeth in X-ray.- Optical and electron microscopy: Depth of focus, Images of Nature, Simple microscopes, Compound microscopes, SEM.- Mars.