26 – Properties of Light Flashcards
photon
electromagnetic radiation described as a particle
electromagnetic radiation can also be described as a wave
speed of light
3 × 108 m/s
vacuum
empty space
light-year
the distance light travels in a year*
*through a vacuum
electromagnetic wave
a wave that is partly electric and partly magnetic and carries energy
emitted by vibrating electric charges.
electromagnetic spectrum
the range of electromagnetic waves extending from radio waves to gamma rays (low to high frequency)
electromagnetic waves from low to high frequency
radio waves
microwaves
infrared
visible light
ultraviolet
x-rays
gamma
relationship between frequency and wavelength
inverse
as frequency increases, wavelength decreases
visible light from low to high frequency
Red
Orange
Yellow
Green
Blue
Indigo
Violet
infrared
electromagnetic waves of frequencies lower than the red of visible light
ultraviolet
electromagnetic waves of frequencies higher than those of violet light
transparent
term applied to materials that allow light to pass through them in straight lines
opaque
term applied to materials that do not allow light to pass through them
glass is transparent to…
visible light, but not ultraviolet or infrared
how light is absorbed by and re-emitted to neighboring atoms
light travels fastest in a…
vacuum
ray
a thin beam of light
shadow
a shaded region that results when light falls on an object and thus cannot reach into the region on the far side of the object
umbra
the darker part of a shadow where all the light is blocked
penumbra
a partial shadow that appears where light from part of the source is blocked and light from another part of the source is not blocked
polarization
the aligning of vibrations in a transverse wave, usually by filtering out waves of other directions
polarization by filtering
unpolarized light becomes polarized by passing through the first filter, which can then be blocked if the second filter is rotated 90° from the first
polarization by reflection
light waves that reflect off horizontal surfaces is aligned horizontally (polarized)
sunglasses that are “polarized” are aligned vertically to filter out light waves that reflect off horizontal surfaces
3D movies
using two projectors, two images are projected on the screen: one polarized vertically and the other horizontally
these images reflect off the screen to the viewer
the viewer uses special glasses (one lens is polarized vertically and the other lens is polarized horizontally) so that each eye receives only one of the images
solar eclipse
an event in which the Moon blocks light from the Sun and the Moon’s shadow falls on part of the Earth
lunar eclipse
an event in which the Moon passes into the shadow of Earth
