Photons
massless bundles of concentrated electromagnetic energy
What is the nature of light?
Dual; light is both a particle and a wave
light year
the distance light travels in one year
electromagnetic wave
a wave that consists of oscillating electric and magnetic fields, which radiate outward at the speed of light (can travel through the vacuum of space)
electromagnetic spectrum
All of the frequencies or wavelengths of electromagnetic radiation
infrared light
Infrared light has longer wavelengths, penetrates more deeply, has less energy, and produces more heat than visible light; makes up 60 percent of natural sunlight.
ultraviolet light
part of the electromagnetic spectrum that consists of waves with frequencies higher than those of visible light and lower than those of x-rays
transparent
materials that transmit light
opaque
impossible to see through; preventing the passage of light
ray
a thin beam of light
shadow
An area from which light is blocked.
umbra
The darkest part of a shadow
penumbra
the lighter part of a shadow where light is partially blocked (the fuzzy part)
polarization of light
The property of light describing how the electric and magnetic fields of light waves are aligned; light is said to be polarized when all of the photons have their electric and magnetic fields aligned in some particular way.