Electromagnetic Waves Do not require a medium to travel, unlike mechanical waves Exhibits interactions that are true for all waves: Reflection (scatter), Refraction, Diffraction, and Interference Speed of light ~300,000,000 m/s in a vacuum (sound in solids = 5,200 m/s)
What happens to light when it enters matter? 3. Transmitted – passing of EM waves through a medium (includes refraction) *transparent –light passes through *translucent – light passes through but is scattered *opaque-light does not pass through but reflects or absorbs 2. Absorbed – the disappearance of an EM wave into the medium. This light is converted to heat. 1. Reflected – includes scattering which is the spreading out of light rays in all directions
Two factors determine the color of an object: 1.The wavelengths that the object itself reflects or absorbs 2.The color of the light that shines on the object
Diffraction spike - Diffraction spikes are lines radiating from bright light sources in reflecting telescope images. They are artifacts caused by light diffracting around the support vanes of the secondary mirror. Refracting telescopes and their photographic images do not have the same problem
Produces light by heating up, so it much of the energy ends up as heat. Only 10% of the energy is converted to visible light. The rest is converted to infrared.
Fluorescent light – filled with a mercury vapor and other gases that give off UV light when an electric current passes through it.
Chromatophores are pigment-containing and light-reflecting cells found in amphibians, fish, reptiles, crustaceans, and cephalopods.
What is the name for the production of light from high temperatures or intense heat? INCANDESCENCE What is the name for the production of light from chemical reactions? BIOLUMINESCENCE What is the production of light when a material absorbs EM radiation of one wavelength and give off EM radiation of a different wavelength? FLUORESCENCE
RED SHIFT (Doppler Effect) It is the fact that sound travels in waves that allows the Doppler effect to happen. Electromagnetic radiation, which includes visible light, also travels in waves, so the Doppler effect happens with light too: as an object travels towards you at speed, the light waves being emitted (or reflected) by it are squished color.
Red Shift This spectral line will move towards the red end of the spectrum when light from a star is moving away