Light and Optics Flashcards
transverse waves that consist of an oscillating electric field and an oscillating magnetic field
electromagnetic waves
relative orientation of electric and magnetic fields
perpendicular
the range of frequencies and wavelengths found in EM waves
electromagnetic spectrum (RMIVUX G)
runs from approximately ____ (red) to ____ (violet)
visible spectrum (700 nm to 400 nm)
the rebounding of incident light waves at the boundary of a medium
reflection
states that the incident angle will equal the angel of reflection, as measured from the normal
law of reflection
line drawn perpendicular to the boundary of a medium
normal line
inverted image formed from light that converges at the position of the image
real image
upright image formed from light that only appears to be coming from the position of the image but doesn’t actually converge there
virtual image
produce virtual, upright images; images are always the same size as the object
plane mirrors
have a center, radius of curvature, and a focal point; can produce either virtual, upright images or real, inverted images; can be concave or convex
spherical mirrors
distance between center of curvature (c) and the mirror
radius of curvature
focal point (ƒ)
ƒ = r / 2
where:
ƒ = focal point
r = radius of curvature
converging systems that can produce virtual, upright images or real, inverted images, depending on the placement of the object relative to the focal point
concave mirrors
diverging systems that can only produce virtual, upright images
convex mirrors
relationship between distances in geometrical optics:
1/ƒ = 1/o + 1/i = 2/r
where: ƒ = focal length o = distance between object and mirror i = distance between image and mirror r = radius of curvature
dimensionless value; ratio of image distance/size to object distance/size; negative value signifies inverted image, positive value signifies upright image
magnification
magnification (m)
m = -i/o
where:
m = magnification
i = distance between image and mirror
o = distance between object and mirror
ray diagrams for concave mirrors:
object is placed beyond F (focal point)
ray diagrams for concave mirrors:
object is placed at F (focal point)
ray diagrams for concave mirrors:
object is placed between F (focal point) and the mirror
ray diagram for convex mirrors:
the bending of light as it passes from one medium to another and changes speed
refraction
dimensionless quantity used to describe medium that determines change in the speed of light
index of refraction (n)
index of refraction (n)
n = c/v
where:
n = index of refraction
c = speed of light in vacuum (3x10^8 m/s)
v = speed of light in medium
speed of light and index of refraction of air
approximately equal to that of a vacuum:
c = 3x10^8 m/s
n = 1
states that there is an inverse relationship between the index of refraction and the sine of the angle of refraction (measured from the normal)
Snell’s law (law of refraction)
Snell’s law (law of refraction)
n(1) sin θ(1) = n(2) sin θ(2)
where:
n(1) and θ(1) refer to medium light comes from
n(2) and θ(2) refer to medium light enters
occurs when light cannot be refracted out of a medium and is instead reflected back inside the medium; happens when light moves from medium with a higher index of refraction to a medium with a lower index of refraction with a high incident angle
total internal reflection
minimum incident angle at which total internal reflection occurs; refracted angle θ(2) = 90°; refracted light passes along interface between two media
critical angle (θ(c))
when light enters a medium with a higher index of refraction (n(2) > n(1))
light bends toward the normal (θ(2) < θ(1))
when light enters a medium with a lower index of refraction (n(2) < n(1))
light bends away from the normal (θ(2) > θ(1))
refract light to form images of objects
lenses
have focal points on each side
thin symmetrical lenses
converging systems that can produce virtual, upright images or real, inverted images
convex lenses ( () )
diverging systems that can only produce virtual, upright images
concave lenses ( )( )
use required for lenses with non negligible thickness
lensmaker’s equation
lensmaker’s equation
P = 1/ƒ = (n-1) (1/r(1) - 1/r(2))
where:
ƒ = focal length
n = index of refraction of lens material
r(1) and r(2) = radius of curvature of first and second lenses
used by optometrists to describe lens strength; unit = diopters
power (P)
power (P)
P = 1/ƒ
where:
ƒ = focal length
addition of multiple lens systems:
focal length-
power-
magnification-
1/f = 1/f(1) + 1/f(2) + 1/f(3) + ... + 1/f(n) P = P(1) + P(2) + P(3) + ... + P(n) m = m(1) x m(2) x m(3) x ... x m(n)
errors that spherical mirrors and lenses are subject to because of their imperfections
spherical abberations
when various wavelengths of light separate form each other; such as the splitting of white light into its component colors using a prism
dispersion
a dispersive effect within a spherical lens; light dispersions within the lens leads to the formation of a rainbow halo at the edge of the image
chromatic abberation
the bending and spreading out of light waves as they pass through a narrow slit; may produce a large central light fringe surrounded by alternating light and dark fringes with the addition of a lens
diffraction
addition of displacements of waves when they interact with each other; supports the wave theory of light
interference
shows the constructive and destructive interference of waves that occur as light passes through parallel slits resulting in minima (dark fringes) and maxima (bright fringes) of intensity
Young’s double-slit experiment
light in which the electric fields of all the waves are oriented in the same direction; electric field vectors are parallel
plane-polarized light
turns unpolarized light passing through it into plane-polarized light
polarizer
all of the light rays have electric fields with equal intensity but constantly rotating direction; created by exposing unpolarized light to special pigments
circular polarized light
