Exam 2 Flashcards
1 Angstrom
10^-10 m
Speed of Light Facts
1/10 second to cross the
Atlantic. 8 minutes to get from the Sun
to the Earth. 4.3 years to reach Earth from
the nearest star
Ole Romer
Used the eclipse of Jupiters moon to determine speed of light
Fizeau-Foucault
Used a spinning mirror to determine speed of light.
Michelson-Morley
Michelson and Morley performed an experiment with a rotating interferometer.
Gamma Rays
given off naturally by radioactive materials, and are part of the fallout after a nuclear explosion. They have very short wavelengths, and can therefore travel through material, including lead, and can damage living tissue.
X-Ray
given this name because their discover was unsure of what they were. They pass through flesh, but are absorbed by bone, which makes them useful for medical diagnostics. The wavelengths match the spacings between atoms in solids, which makes them useful for studies of material properties. Small
doses are safe, but large doses can be harmful to living tissue.
UV
cause us to tan and help the skin to produce vitamin D. Large amounts are dangerous and may cause skin cancer. Most UV light from the sun is absorbed by the ozone layer. UV blacklights are used to make bright colors appear brighter.
Visible Light
appears white as a whole, but is made of many colors. Red and violet light have wavelengths of 7500 and 4000 Å, respectively, which correspond to frequencies of 4x1014 and 7.5x1014 Hz.
IR
transmit heat. They can be used to
see objects in the dark. They are also used for TV remote controls.
Microwaves
very short radio waves, used in ovens. Also used for radar.
Radio Waves
are at the low end of the frequency spectrum, are used
to broadcast radio and TV.
nanometer
10^-9m
red frequency
4x10^14 Hz
violet frequency
7.5x10^14 Hz
What light can pass through glass?
Visible light
Speed of Light in Water
.75c
Speed of Light in Glass
.67c
Lunar Eclipse
Moon in Earths Shadow
Solar Eclipse
Shadow of the Moon on the Earth
Umbra
Total Eclipse
Penumbra
Partial Eclipse
Cones
Over 160,000 in each square millimeter of the fovea, None on the periphery, Responsible for sharp images, There are 3 types of cones, They contain photopigment molecules that absorb light and stimulate nerves, Provide color vision
Rods
None on fovea, Responsible for peripheral vision, Sensitive to: dim light, motion, small variations in intensity
Color blind
About 8% of males and 1% of females have some form
of color deficiency
rayleigh scattering
Occurs when resonant frequencies are higher than the frequencies of the particles scattering, More effective at short wavelengths (the blue end of the visible spectrum).
Reflection
occurs as light interacts with the free electrons in a material
Concave mirror beyond focal
Real image, Inverted
concave mirror within focal
• Virtual image, Upright
convex mirror
Virtual image, Upright
Refraction
Bending of a wave as it moves from one medium to another, A consequence of the fact that the wavespeed depends on the
medium.
law of refraction
01 > 02 leads to n1 < n2
mirages
Mirages occur because light travels faster in hot air than in cool air
