optics Flashcards
electromagnetic waves
waves that do not need a medium to travel in
how are electromagnetic waves created
by an oscillating electric and magnetic fields
what are all forms of electromagnetic waves characterized by
their range of frequencies and wavelengths
when light changes mediums, what else changes?
its speed and direction
refraction
the idea that the more the difference in speed, the greater the light bends when it changes mediums
illuminance
the intensity of light falling onto a surface. measured in lux
illuminance equation
E=θv / 4 πr^2 (θv is the luminous flux which is given en in lumens)
polarized light
light where the EM wave only vibrates in one direction. Light will be polarized in the direction of the electric field
what happens when unpolarized light passes through a polarizer?
the final intensity of the light will be one half of the initial intensity of the light wave
what direction is a beam of light polarized in?
the direction of the polarizers transmission axis
law of malus
If =Iicos^2θ
l= intensity
reflection
when a wave hits a surface or a boundary and bounces off in a different direction
when will waves be reflected
anytime they encounter a boundary between two mediums
wave front
the surface over which the phase of a wave is constant. given that all particles of the medium are undergoing the same motion
sperical wave front
where waves move outward in three dimensions with rays that point radically outward
plane wave front
where the waves move outward in one direction with the rays pointing in that same direction
what angle will rays be at to wave fronts
right angles
normal line
the line that is perpendicular to the surface is placed so that its located where the ray that enters the mirror travels
incident ray
the ray that hits the mirror then is reflected by the mirror at the location of the normal line
angle of incidence
the angle between the incident ray and the normal
angle of reflection
the angle between the mirror and the reflected ray
law of reflection
when light is reflected off a surface the angle of incidence equals the angle of reflection
specular reflection
when a beam of light is reflected from a smooth surface
diffuse reflection
when a beam of light is reflected off a rough surface
plane mirror
a perfectly flat mirror
what do plane mirrors create
virtual image, same size as the object, the image will be upright, but reversed right to left.
concave mirror
a mirror thats curved in
convex mirror
a mirror that is flexed out, bulges outwards like the surface of a ball
center of curvature of a spherical mirror
center of the spherical shell with a radius of R of which the curved mirror is a section of
principle axis
a straight line drawn through the center of curvature and the midpoint of the mirror. the center of curvature lies on this line and it intersects the mirror at right angles
where will the rays converge on a concave mirror?
infront of the mirror
focal point
where the rays of a mirror reflect and converge
focal length
distance between the surface of the mirror to the focal point
the equation for focal length of a CONCAVE mirror
f= 1/2 R
where will rays of light that are parallel to the principle axis always reflect on a concave mirror
through the focal point
which way do rays spread on a convex mirror
outwards
does light pass through the focal point on a convex mirror?
no
incoming rays of light that are parallel to the principal axis of a convex mirror are…
spread out
equation for focal length on a CONVEX mirror
f= - 1/2R
the focal length of a mirror will be positive if…
the focal point is in front of the mirror
CONCAVE mirror always have a ___ focal length
positive
the focal length will always be negative if
the focal point is behind the mirror
CONVEX mirrors will always have a ___ focal length
negative
mirror equation
1/do + 1/di = 1/f
when will the image distance be positive
if its infront of a mirror
when will the image distance be negative
if the image is behind the mirror
what does a positive image distance tell you
its a real image
what does a negative image distance tell you
its a virutal image