Physics- Chapter 20: The Refraction of Light

optical density

a material’s resistance to the transmission of light waves

3\.00 x 10^8 m/s

speed of light (in air/vacuum)

wavelength decreases in optically denser medium

how is wavelength and speed affected when it enters a new medium

it is unaffected

how is frequency affected when it enters a new medium

refraction

the bending of light rays at the boundary between two media

refractive index

relates the speed of light in a vacuum to the speed of light in a particular medium

refractometer

an instrument used to measure the refractive index of an object (specifically diamonds)

diamonds

which substance is the densest of all materials and therefore has the highest refractive index

the first law of refraction

the angle of incidence times the the refractive index equals the angle of refraction times the refractive index

Snell’s law

relationship derived from the first law

the second law of refraction

the incident ray, the normal, and the refracted ray all lie on the same plane

principle of reversibility

traced in reverse by an ray coming along the path in the opposite direction

mirage

the refraction of sunlight as it passes through hot, expanding air at the ground level

total internal reflection

occurs when the angle of incidence reaches the critical angle and no refraction occurs- only reflection

when light comes to the boundary of a medium of lower density

when may total internal reflection occur

critical angle

the angle of incidence at which the angle of refraction becomes 90 degrees

lens

a transparent object with two nonparallel surfaces joining at a narrow rim

convex lens

a bulging surfacce

a caved-in surface

concave lens

a flat surface

planar lens

converging lens

lenses that redirect parallel rays toward a point of convergence

double convex lenses

the most important converging lenses

diverging lenses

lenses that spread parallel rays apart

double concave lenses

the most important diverging lenses

the opposite side of the lens from the object

where are real images located in relation to a lens

on the same side of the lens as the object

where are virtual images located

converging lenses

what type of lens has a positive focal length

diverging lenses

what type of lens has a negative focal length

the radius of curvature and refractive index

what does the focal length of a lens depend on

myopia

focal point before retina (nearsightedness)

hyperopia

focal point after retina (farsightedness)

diopters

the power of a lens in measured in ____

thin lens

a lens whose thickness is small compared the the len’s radius of curvature

reduced

upright

virtual

no matter the distance the image is ____ in a diverging lens

normal

the perpendicular to the plane at the point of tangency

prinicpal axis

perpendicular to the lens plane through the optical center

optical center

the center of the lens

optical plane

a plane perpendicular to the principal axis at the optical center

focal length

the distance from the optical center to the principal focal point

principal focal point

a point of convergence on the opposite side of the lens

secondary focal point

located by rays moving from right to left through the lens

parallel ray

travels parallel to the principal axis and the refracts through the primary focal point

central ray

passes through the optical center without deviation

focal ray

travels through the secondary focal point then refracts parallel to the principal axis