exam 2

wave-particle duality

the theory that electromagnetic radiation (light) may be treated as either a particle or electromagnetic wave

parallax

the shift in an object’s perceived position caused by the observer’s motion. the closer something is, the bigger parallax shift it appears to have

properties of light

speed of light in empty space is constant, light is made up of electric and magnetic energy, light can travel through a vacuum

lambda

also called a wavelength, it corresponds with distance between the peaks of waves and falling nodes

frequency

1/T, how many cycles there are per second, how often is the wave going up and down?

interference

2 waves can occupy the same space

constructive interference

when 2 waves are the same and occupying the same space, they both amplify their wave together

destructive interference

when 2 waves are occupying the same space but theyre opposites, they zero each other out (a flat line)

photon

particle of light

All waves need a medium to pass through except for?

light because it is an electromagnetic wave that can pass through empty space

inverse square law

the apparent brightness of a body decreases inversely as the square of its distance. in other words, if you double the distance from a light source, the intensity of the light is reduced to ¼ of its original value

arc minute

a unit of angular size, 1/60 of a degree. 3600 arc seconds are in 1 degree

What happens to the speed of light when it travels through a material?

it becomes slower

proper motion

stars moving across our line of sight show a steady, straight-line change in position over time