College Physics

# Glossary

axis of a polarizing filter
the direction along which the filter passes the electric field of an EM wave
birefringent
crystals that split an unpolarized beam of light into two beams
Brewster’s angle
$θb=tan−1n2n1,θb=tan−1n2n1, size 12{θ rSub { size 8{b} } ="tan" rSup { size 8{ - 1} } left ( { {n rSub { size 8{2} } } over {n rSub { size 8{1} } } } right ),} {}$ where $n2n2$ is the index of refraction of the medium from which the light is reflected and $n1n1$ is the index of refraction of the medium in which the reflected light travels
Brewster’s law
$tanθb=n2n1tanθb=n2n1$, where $n1n1$ is the medium in which the incident and reflected light travel and $n2n2$ is the index of refraction of the medium that forms the interface that reflects the light
coherent
waves are in phase or have a definite phase relationship
confocal microscopes
microscopes that use the extended focal region to obtain three-dimensional images rather than two-dimensional images
constructive interference for a diffraction grating
occurs when the condition $dsinθ=mλ(for m=0,1,–1,2,–2,…)dsinθ=mλ(for m=0,1,–1,2,–2,…)$ is satisfied, where $dd size 12{d} {}$ is the distance between slits in the grating, $λλ size 12{λ} {}$ is the wavelength of light, and $mm size 12{m} {}$ is the order of the maximum
constructive interference for a double slit
the path length difference must be an integral multiple of the wavelength
contrast
the difference in intensity between objects and the background on which they are observed
destructive interference for a double slit
the path length difference must be a half-integral multiple of the wavelength
destructive interference for a single slit
occurs when $Dsinθ=mλ,(form=1,–1,2,–2,3,…)Dsinθ=mλ,(form=1,–1,2,–2,3,…) size 12{D"sin"θ= ital "mλ",~m="1,""2,""3," dotslow } {}$, where $DD size 12{D} {}$ is the slit width, $λλ size 12{λ} {}$ is the light’s wavelength, $θθ size 12{θ} {}$ is the angle relative to the original direction of the light, and $mm size 12{m} {}$ is the order of the minimum
diffraction
the bending of a wave around the edges of an opening or an obstacle
diffraction grating
a large number of evenly spaced parallel slits
direction of polarization
the direction parallel to the electric field for EM waves
horizontally polarized
the oscillations are in a horizontal plane
Huygens’s principle
every point on a wavefront is a source of wavelets that spread out in the forward direction at the same speed as the wave itself. The new wavefront is a line tangent to all of the wavelets
incoherent
waves have random phase relationships
interference microscopes
microscopes that enhance contrast between objects and background by superimposing a reference beam of light upon the light emerging from the sample
optically active
substances that rotate the plane of polarization of light passing through them
order
the integer $mm size 12{m} {}$ used in the equations for constructive and destructive interference for a double slit
phase-contrast microscope
microscope utilizing wave interference and differences in phases to enhance contrast
polarization
the attribute that wave oscillations have a definite direction relative to the direction of propagation of the wave
polarization microscope
microscope that enhances contrast by utilizing a wave characteristic of light, useful for objects that are optically active
polarized
waves having the electric and magnetic field oscillations in a definite direction
Rayleigh criterion
two images are just resolvable when the center of the diffraction pattern of one is directly over the first minimum of the diffraction pattern of the other
reflected light that is completely polarized
light reflected at the angle of reflection $θbθb size 12{θ rSub { size 8{b} } } {}$, known as Brewster’s angle
thin film interference
interference between light reflected from different surfaces of a thin film
ultraviolet (UV) microscopes
microscopes constructed with special lenses that transmit UV rays and utilize photographic or electronic techniques to record images
unpolarized
waves that are randomly polarized
vertically polarized
the oscillations are in a vertical plane
wavelength in a medium
$λ n=λ/nλ n=λ/n size 12{λ rSub { size 8{n} } =λ/n} {}$, where $λλ size 12{λ} {}$ is the wavelength in vacuum, and $nn size 12{n} {}$ is the index of refraction of the medium