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index of refraction : for a material, the ratio of the speed of light in a vacuum to that in a material
https://openstax.org/books/university-physics-volume-3/pages/1-key-terms
law of reflection : angle of reflection equals the angle of incidence
https://openstax.org/books/university-physics-volume-3/pages/1-key-terms
law of refraction : when a light ray crosses from one medium to another, it changes direction by an amount that depends on the index of refraction of each medium and the sines of the angle of incidence and angle of refraction
https://openstax.org/books/university-physics-volume-3/pages/1-key-terms
Malus’s law : whereI0I0is the intensity of the polarized wave before passing through the filter
https://openstax.org/books/university-physics-volume-3/pages/1-key-terms
optically active : substances that rotate the plane of polarization of light passing through them
https://openstax.org/books/university-physics-volume-3/pages/1-key-terms
polarization : attribute that wave oscillations have a definite direction relative to the direction of propagation of the wave
https://openstax.org/books/university-physics-volume-3/pages/1-key-terms
polarized : refers to waves having the electric and magnetic field oscillations in a definite direction
https://openstax.org/books/university-physics-volume-3/pages/1-key-terms
ray : straight line that originates at some point
https://openstax.org/books/university-physics-volume-3/pages/1-key-terms
refraction : changing of a light ray’s direction when it passes through variations in matter
https://openstax.org/books/university-physics-volume-3/pages/1-key-terms
total internal reflection : phenomenon at the boundary between two media such that all the light is reflected and no refraction occurs
https://openstax.org/books/university-physics-volume-3/pages/1-key-terms
unpolarized : refers to waves that are randomly polarized
https://openstax.org/books/university-physics-volume-3/pages/1-key-terms
vertically polarized : oscillations are in a vertical plane
https://openstax.org/books/university-physics-volume-3/pages/1-key-terms
wave optics : part of optics dealing with the wave aspect of light
https://openstax.org/books/university-physics-volume-3/pages/1-key-terms
The speed of light in a vacuum isc=2.99792458×108m/s≈3.00×108m/sc=2.99792458×108m/s≈3.00×108m/s.
https://openstax.org/books/university-physics-volume-3/pages/1-summary
The index of refraction of a material isn=c/v,n=c/v,wherevis the speed of light in a material andcis the speed of light in a vacuum.
https://openstax.org/books/university-physics-volume-3/pages/1-summary
The ray model of light describes the path of light as straight lines. The part of optics dealing with the ray aspect of light is called geometric optics.
https://openstax.org/books/university-physics-volume-3/pages/1-summary
Light can travel in three ways from a source to another location: (1) directly from the source through empty space; (2) through various media; and (3) after being reflected from a mirror.
https://openstax.org/books/university-physics-volume-3/pages/1-summary
When a light ray strikes a smooth surface, the angle of reflection equals the angle of incidence.
https://openstax.org/books/university-physics-volume-3/pages/1-summary
A mirror has a smooth surface and reflects light at specific angles.
https://openstax.org/books/university-physics-volume-3/pages/1-summary
Light is diffused when it reflects from a rough surface.
https://openstax.org/books/university-physics-volume-3/pages/1-summary
The change of a light ray’s direction when it passes through variations in matter is called refraction.
https://openstax.org/books/university-physics-volume-3/pages/1-summary
The law of refraction, also called Snell’s law, relates the indices of refraction for two media at an interface to the change in angle of a light ray passing through that interface.
https://openstax.org/books/university-physics-volume-3/pages/1-summary
The incident angle that produces an angle of refraction of90°90°is called the critical angle.
https://openstax.org/books/university-physics-volume-3/pages/1-summary
Total internal reflection is a phenomenon that occurs at the boundary between two media, such that if the incident angle in the first medium is greater than the critical angle, then all the light is reflected back into that medium.
https://openstax.org/books/university-physics-volume-3/pages/1-summary
Fiber optics involves the transmission of light down fibers of plastic or glass, applying the principle of total internal reflection.
https://openstax.org/books/university-physics-volume-3/pages/1-summary
Cladding prevents light from being transmitted between fibers in a bundle.
https://openstax.org/books/university-physics-volume-3/pages/1-summary
Diamonds sparkle due to total internal reflection coupled with a large index of refraction.
https://openstax.org/books/university-physics-volume-3/pages/1-summary
The spreading of white light into its full spectrum of wavelengths is called dispersion.
https://openstax.org/books/university-physics-volume-3/pages/1-summary
Rainbows are produced by a combination of refraction and reflection, and involve the dispersion of sunlight into a continuous distribution of colors.
https://openstax.org/books/university-physics-volume-3/pages/1-summary
Dispersion produces beautiful rainbows but also causes problems in certain optical systems.
https://openstax.org/books/university-physics-volume-3/pages/1-summary
According to Huygens’s principle, every point on a wave front is a source of wavelets that spread out in the forward direction at the same speed as the wave itself. The new wave front is tangent to all of the wavelets.
https://openstax.org/books/university-physics-volume-3/pages/1-summary
A mirror reflects an incoming wave at an angle equal to the incident angle, verifying the law of reflection.
https://openstax.org/books/university-physics-volume-3/pages/1-summary
The law of refraction can be explained by applying Huygens’s principle to a wave front passing from one medium to another.
https://openstax.org/books/university-physics-volume-3/pages/1-summary
The bending of a wave around the edges of an opening or an obstacle is called diffraction.
https://openstax.org/books/university-physics-volume-3/pages/1-summary
Polarization is the attribute that wave oscillations have a definite direction relative to the direction of propagation of the wave. The direction of polarization is defined to be the direction parallel to the electric field of the EM wave.
https://openstax.org/books/university-physics-volume-3/pages/1-summary
Unpolarized light is composed of many rays having random polarization directions.
https://openstax.org/books/university-physics-volume-3/pages/1-summary
Unpolarized light can be polarized by passing it through a polarizing filter or other polarizing material. The process of polarizing light decreases its intensity by a factor of 2.
https://openstax.org/books/university-physics-volume-3/pages/1-summary
The intensity,I, of polarized light after passing through a polarizing filter isI=I0cos2θI=I0cos2θ, whereI0I0is the incident intensity andθθis the angle between the direction of polarization and the axis of the filter.
https://openstax.org/books/university-physics-volume-3/pages/1-summary
Polarization is also produced by reflection.
https://openstax.org/books/university-physics-volume-3/pages/1-summary
Brewster’s law states that reflected light is completely polarized at the angle of reflectionθbθb, known as Brewster’s angle.
https://openstax.org/books/university-physics-volume-3/pages/1-summary
Polarization can also be produced by scattering.
https://openstax.org/books/university-physics-volume-3/pages/1-summary
Several types of optically active substances rotate the direction of polarization of light passing through them.
https://openstax.org/books/university-physics-volume-3/pages/1-summary
d o = − d i d o = − d i
https://openstax.org/books/university-physics-volume-3/pages/2-key-equations
f = R 2 f = R 2
https://openstax.org/books/university-physics-volume-3/pages/2-key-equations
1 d o + 1 d i = 1 f 1 d o + 1 d i = 1 f
https://openstax.org/books/university-physics-volume-3/pages/2-key-equations
m = h i h o = − d i d o m = h i h o = − d i d o
https://openstax.org/books/university-physics-volume-3/pages/2-key-equations
+ for concave mirror − for convex mirror + for concave mirror − for convex mirror
https://openstax.org/books/university-physics-volume-3/pages/2-key-equations
+ for real object − for virtual object + for real object − for virtual object
https://openstax.org/books/university-physics-volume-3/pages/2-key-equations
+ for real image − for virtual image + for real image − for virtual image
https://openstax.org/books/university-physics-volume-3/pages/2-key-equations
+ for upright image − for inverted image + for upright image − for inverted image
https://openstax.org/books/university-physics-volume-3/pages/2-key-equations
h i = ( n 2 n 1 ) h o h i = ( n 2 n 1 ) h o
https://openstax.org/books/university-physics-volume-3/pages/2-key-equations
n 1 d o + n 2 d i = n 2 − n 1 R n 1 d o + n 2 d i = n 2 − n 1 R
https://openstax.org/books/university-physics-volume-3/pages/2-key-equations
1 d o + 1 d i = 1 f 1 d o + 1 d i = 1 f
https://openstax.org/books/university-physics-volume-3/pages/2-key-equations
1 f = ( n 2 n 1 − 1 ) ( 1 R 1 − 1 R 2 ) 1 f = ( n 2 n 1 − 1 ) ( 1 R 1 − 1 R 2 )
https://openstax.org/books/university-physics-volume-3/pages/2-key-equations
m ≡ h i h o = − d i d o m ≡ h i h o = − d i d o
https://openstax.org/books/university-physics-volume-3/pages/2-key-equations
P = 1 f P = 1 f
https://openstax.org/books/university-physics-volume-3/pages/2-key-equations
P total = P lens 1 + P lens 2 + P lens 3 + ⋯ P total = P lens 1 + P lens 2 + P lens 3 + ⋯
https://openstax.org/books/university-physics-volume-3/pages/2-key-equations
M = θ image θ object M = θ image θ object
https://openstax.org/books/university-physics-volume-3/pages/2-key-equations
M = ( 25 cm L ) ( 1 + L − ℓ f ) M = ( 25 cm L ) ( 1 + L − ℓ f )
https://openstax.org/books/university-physics-volume-3/pages/2-key-equations
25 cm f ≤ M ≤ 1 + 25 cm f 25 cm f ≤ M ≤ 1 + 25 cm f
https://openstax.org/books/university-physics-volume-3/pages/2-key-equations
M net = m obj M eye = − d i obj ( f eye + 25 cm ) f obj f eye M net = m obj M eye = − d i obj ( f eye + 25 cm ) f obj f eye
https://openstax.org/books/university-physics-volume-3/pages/2-key-equations
aberration : distortion in an image caused by departures from the small-angle approximation
https://openstax.org/books/university-physics-volume-3/pages/2-key-terms
accommodation : use of the ciliary muscles to adjust the shape of the eye lens for focusing on near or far objects
https://openstax.org/books/university-physics-volume-3/pages/2-key-terms
angular magnification : ratio of the angle subtended by an object observed with a magnifier to that observed by the naked eye
https://openstax.org/books/university-physics-volume-3/pages/2-key-terms
apparent depth : depth at which an object is perceived to be located with respect to an interface between two media
https://openstax.org/books/university-physics-volume-3/pages/2-key-terms
Cassegrain design : arrangement of an objective and eyepiece such that the light-gathering concave mirror has a hole in the middle, and light then is incident on an eyepiece lens
https://openstax.org/books/university-physics-volume-3/pages/2-key-terms
charge-coupled device (CCD) : semiconductor chip that converts a light image into tiny pixels that can be converted into electronic signals of color and intensity
https://openstax.org/books/university-physics-volume-3/pages/2-key-terms
coma : similar to spherical aberration, but arises when the incoming rays are not parallel to the optical axis
https://openstax.org/books/university-physics-volume-3/pages/2-key-terms
compound microscope : microscope constructed from two convex lenses, the first serving as the eyepiece and the second serving as the objective lens
https://openstax.org/books/university-physics-volume-3/pages/2-key-terms
concave mirror : spherical mirror with its reflecting surface on the inner side of the sphere; the mirror forms a “cave”
https://openstax.org/books/university-physics-volume-3/pages/2-key-terms
converging (or convex) lens : lens in which light rays that enter it parallel converge into a single point on the opposite side
https://openstax.org/books/university-physics-volume-3/pages/2-key-terms
convex mirror : spherical mirror with its reflecting surface on the outer side of the sphere
https://openstax.org/books/university-physics-volume-3/pages/2-key-terms
curved mirror : mirror formed by a curved surface, such as spherical, elliptical, or parabolic
https://openstax.org/books/university-physics-volume-3/pages/2-key-terms
diverging (or concave) lens : lens that causes light rays to bend away from its optical axis
https://openstax.org/books/university-physics-volume-3/pages/2-key-terms
eyepiece : lens or combination of lenses in an optical instrument nearest to the eye of the observer
https://openstax.org/books/university-physics-volume-3/pages/2-key-terms
far point : furthest point an eye can see in focus
https://openstax.org/books/university-physics-volume-3/pages/2-key-terms
farsightedness (or hyperopia) : visual defect in which near objects appear blurred because their images are focused behind the retina rather than on the retina; a farsighted person can see far objects clearly but near objects appear blurred
https://openstax.org/books/university-physics-volume-3/pages/2-key-terms
first focus or object focus : object located at this point will result in an image created at infinity on the opposite side of a spherical interface between two media
https://openstax.org/books/university-physics-volume-3/pages/2-key-terms
focal length : distance along the optical axis from the focal point to the optical element that focuses the light rays
https://openstax.org/books/university-physics-volume-3/pages/2-key-terms
focal plane : plane that contains the focal point and is perpendicular to the optical axis
https://openstax.org/books/university-physics-volume-3/pages/2-key-terms
focal point : for a converging lens or mirror, the point at which converging light rays cross; for a diverging lens or mirror, the point from which diverging light rays appear to originate
https://openstax.org/books/university-physics-volume-3/pages/2-key-terms
image distance : distance of the image from the central axis of the optical element that produces the image
https://openstax.org/books/university-physics-volume-3/pages/2-key-terms
linear magnification : ratio of image height to object height
https://openstax.org/books/university-physics-volume-3/pages/2-key-terms
magnification : ratio of image size to object size
https://openstax.org/books/university-physics-volume-3/pages/2-key-terms
near point : closest point an eye can see in focus
https://openstax.org/books/university-physics-volume-3/pages/2-key-terms
nearsightedness (or myopia) : visual defect in which far objects appear blurred because their images are focused in front of the retina rather than on the retina; a nearsighted person can see near objects clearly but far objects appear blurred
https://openstax.org/books/university-physics-volume-3/pages/2-key-terms
net magnification : (MnetMnet) of the compound microscope is the product of the linear magnification of the objective and the angular magnification of the eyepiece
https://openstax.org/books/university-physics-volume-3/pages/2-key-terms
Newtonian design : arrangement of an objective and eyepiece such that the focused light from the concave mirror was reflected to one side of the tube into an eyepiece
https://openstax.org/books/university-physics-volume-3/pages/2-key-terms
object distance : distance of the object from the central axis of the optical element that produces its image
https://openstax.org/books/university-physics-volume-3/pages/2-key-terms
objective : lens nearest to the object being examined.
https://openstax.org/books/university-physics-volume-3/pages/2-key-terms
optical axis : axis about which the mirror is rotationally symmetric; you can rotate the mirror about this axis without changing anything
https://openstax.org/books/university-physics-volume-3/pages/2-key-terms
optical power : (P) inverse of the focal length of a lens, with the focal length expressed in meters. The optical powerPof a lens is expressed in units of diopters D; that is,1D=1/m=1m−11D=1/m=1m−1
https://openstax.org/books/university-physics-volume-3/pages/2-key-terms
plane mirror : plane (flat) reflecting surface
https://openstax.org/books/university-physics-volume-3/pages/2-key-terms
ray tracing : technique that uses geometric constructions to find and characterize the image formed by an optical system
https://openstax.org/books/university-physics-volume-3/pages/2-key-terms
real image : image that can be projected onto a screen because the rays physically go through the image
https://openstax.org/books/university-physics-volume-3/pages/2-key-terms
second focus or image focus : for a converging interface, the point where a bundle of parallel rays refracting at a spherical interface; for a diverging interface, the point at which the backward continuation of the refracted rays will converge between two media will focus
https://openstax.org/books/university-physics-volume-3/pages/2-key-terms
simple magnifier (or magnifying glass) : converging lens that produces a virtual image of an object that is within the focal length of the lens
https://openstax.org/books/university-physics-volume-3/pages/2-key-terms
small-angle approximation : approximation that is valid when the size of a spherical mirror is significantly smaller than the mirror’s radius; in this approximation, spherical aberration is negligible and the mirror has a well-defined focal point
https://openstax.org/books/university-physics-volume-3/pages/2-key-terms
spherical aberration : distortion in the image formed by a spherical mirror when rays are not all focused at the same point
https://openstax.org/books/university-physics-volume-3/pages/2-key-terms
thin-lens approximation : assumption that the lens is very thin compared to the first image distance
https://openstax.org/books/university-physics-volume-3/pages/2-key-terms