Ch 7: 4.24.19 Weekly Quiz material Flashcards
draw/label a diagram demonstrating a principal axis… something (help me out here Dalton, what’s this one about specifically?)
draw/explain the elements of destructive interference.
valley to peak = 180 degrees out of phase = smaller/no wave
waves adding together to make a bigger wave
constructive interference
what is an example of diffraction grating?
the color spokes from a CD (compact disc)
the point where reflected rays intersect in a concave mirror
real focal point
draw/label a diagram of a converging lens and a diverging lens.
why do swirls of color appear in parking lot puddles?
there is a layer of oil on top of the water. light partly reflects off of the oil and partly refracts off of the water, so one incident ray becomes two reflected rays. the thickness of the oil layer causes one color to cancel out via destructive interference and we see its complement.
what causes a mirage of a water puddle on a hot road?
the air just above the road is hot, so a boundary is made between the hot air and the air above it. light crosses the boundary and severely refracts (basically reflects), and we perceive the light as coming from a puddle (self note: why water? b/c it’s a reflection of the blue sky). as we get closer, the angle changes and the mirage disappears.
how waves interact
interference
draw/explain the elements of constructive interference.
peak to peak, valley to valley = in phase = bigger wave
light with random orientation
unpolarized light
why are sunrises/sunsets red?
as sunlight travels through the thicket part of the atmosphere, colors are being absorbed. red is the least absorbed and reaches us the best.
why does the blue sky look dark with polarized sunglasses?
the scattered light that makes the sky blue is partially polarized so the sunglasses act as a second filter.
draw/label a diagram of a concave mirror.
when an object is farther away than the center point of a concave mirror, how will the image be?
inverted, reduced, and real
a curved mirror with light reflecting off the inside surface
concave mirror (converging)
2 examples of total internal reflection?
- fiberoptic cables
- water fountains lit from the bottom
age-related farsightedness
presbyopia
two examples of a convex mirror?
- the outside part of a spoon
- security mirrors
draw/label a diagram of a convex mirror.
when an object is closer than the focal point of a concave mirror, how will the image appear?
upright, enlarged, and virtual.
what causes hyperopia? what corrects this?
- the lens can’t work with the eyeball and focuses light too far back.
- a converging lens corrects this.
light with a specific orientation
polarized light
what causes presbypoia, and what corrects it?
1) over a lifetime, the lens becomes less flexible and focuses light too far back.
2) a converging lens corrects this.
nearsightedness
myopia
how a wave bends around a corner
diffraction
why do diamonds show flashes of color?
dispersion causes the colors to separate out
why is the sky blue?
air molecules absorb sunlight and release the energy as scattered light. violet is the color that is scattered the most, but our eyes see blue better.
equation: focal length
focal length is radius over two.
(thus, R = f * 2)
why can we hear a vacuum down the hall but can only see it if within line of sight to the door?
light waves don’t diffract well around a doorway, but sounds waves do
why is the secondary rainbow fainter with the colors reversed?
for the secondary rainbow, the light bounces twice in the droplet and loses some energy.
why does a grain silo seem to shimmer on a sunny day from across a field?
as the reflected light travels above the field, the air current causes the light to slightly refract one way or the other
the reason stars twinkle is similar (self note: air temperature difference is the reason for air currents to begin with)
why is the mid-day sun yellow-white?
as sunlight travels through the thinnest part of the atmosphere, less colors are absorbed, so what reaches us is a better mix.
a curved mirror with light reflected off the outside surface
convex mirror (diverging)
how does a rainbow form?
the observer is between a water droplet and the sun. light goes into the droplet (refraction) and bounces inside (total internal reflection). the colors spread out (dispersion) and come out the front of the droplet. depending on the angle of view, we see one of the colors.
why is the sky sometimes a hazy white?
particles in the air scatter other colors than blue, but then the colors mix back together to give a hazy white effect.
the point where reflected rays seem to originate in a convex mirror
virtual focal point
when different wavelengths spread out
dispersion
how do polarized sunglasses work?
light that reflects off of water or chrome is partially polarized, so the glasses act as a second filter to block the glare.
when an object is at any distance from a convex mirror, how will the image appear?
upright, reduced, and virtual.
what word describes diamonds showing flashes of color?
“fire”
two examples of a concave mirror are?
- the inside part of a spoon
- mirror surface of a headlight
waves trying to cancel each other out to make a smaller (or no) wave
destructive interference
why are clouds white?
clusters of water droplets scatter different colors of light based on their size. these colors mix back together to make a white cloud.
when an object is between the focal point and the center point of a concave mirror, how will the image appear?
inverted, enlarged, and real.
can our eyes tell the difference between polarized and unpolarized light?
no.
what word describes a bright and shiny diamond?
“brilliance”
why are diamonds bright and shiny?
good total internal reflection causes the light to come out at the top
what causes myopia? what corrects it?
- the lens can’t work with the eyeball and focuses light too soon
- a diverging lens corrects this
