Unit 3 Flashcards
What does color depend on?
Light of a particular frequency being reflected from a surface or transmitted through a source
why is light an EM wave?
because it does not need a medium through which to travel. it does travel through mediums.
why are mirrors the best example of a nearly perfect reflection?
almost all of the light that reaches a mirror is reflected
why do rough surfaces not reflect light as well as smooth surfaces?
because they reflect light in many directions at once
what are two results of refraction of light?
dispersion and total internal reflection
what happens to light that travels through a medium other than a vacuum
absorbed and re-emitted by particles within that medium. The more interactions the light has, the more it slows down and is bent.
total internal reflection
the complete reflection of light back into its original medium
when waves interact with matter, they can be…
reflected, transmitted, or a combination of both.
-Waves that are transmitted can be refracted.
When a wave reaches a boundary between two media, usually…
some or all of the wave bounces back into the first medium.
reflection
the return of a wave back into its original medium
normal
incident rays and reflected rays make equal angles with a line perpendicular to the surface
angle of incidence
the angle between the incident ray and the normal
angle of reflection
angle between the reflected ray and the normal
law of reflection
- states that the angle of incidence = the angle of reflection
- applies to both partially reflected and totally reflected waves
virtual image
- an image that appears to be in a location where light does not reach.
- Plane mirrors produce only virtual images
diffuse reflection
the reflection of light from a rough surface
what happens to sound energy that is not reflected?
it is absorbed or transmitted
reverberations
multiple reflections of sound waves
what happens when a wave that is traveling at an angle changes its speed upon crossing a boundary between two media?
it bends
refraction
the bending of a wave as it crosses the boundary between two media at an angle
when are sound waves refracted?
when parts of a wave front travel at different speeds
-can happen in uneven winds or when sound is traveling through air of uneven temperature
what causes refraction?
- changes in the speed of light as it passes from one medium to another
- or variations in the temperatures and densities of the same medium
mirage
appearance of a distorted image. causes by the refraction of light in Earth’s atmosphere.
since different frequencies of light travel at different speeds in transparent materials, they will refract…
differently and bend at different angles
dispersion
separation of light into colors arranged according to their frequency
what is needed to see a rainbow?
- sun must be shining in one part of the sky
- water droplets in a cloud or in falling rain must be in the opposite part of the sky.
critical angle
the angle of incidence that results in the light being refracted at an angle of 90 degrees with respect to the normal
when does total internal reflection occur?
when the angle of incidence is larger than the critical angle
optical fibers
transparent fibers that pipe light from one place to another
for a reflection in a plane mirror…
- object size = object distance
- object distance = image distance
in what way does the law of reflection hold for curved mirrors?
the sizes and distances of object and image are no longer equal
virtual image formed by convex mirror
smaller and closer to the mirror than object is
virtual image formed by concave mirror
can be larger and more distant than the object
what is meant by the idea that a surface may be polished for some waves and rough for others?
the surface is considered polished if differences in elevations in a surface are small (less than 1/8 of the wavelength of light that falls)
echo
reflected sound