Download ch.16_18 vocabulary

Chapters 16, 17,& 18 Vocabulary
Light-electromagnetic radiation with wavelengths from 400 to 700 nm
Ray model-light moves in a straight-line path through a medium
Luminous-a body that emits light waves
Illuminated-a body that reflects light waves produced by and outside source
Luminous flux-the rate at which light is emitted from a light source; measured in lumens
Lumen-unit of luminous flux
Illuminance-the rate at which light falls on a surface; measured in lux
Lux-unit of illuminance; lumens per square unit
Candela-the SI base unit of luminous intensity; candle power
Luminous intensity-the luminous flux that falls on one square meter of a sphere one
meter in radius
Transparent-a material that transmits light without distorting images
Translucent-a material that transmits light but distorts its path
Opaque-a material that absorbs or reflects light, not allowing objects to be seen through it
Spectrum-the ordered arrangement of wavelengths
Primary color-color from which other colors can be derived
Secondary color-color formed by a pair of primary colors
Complementary color-two colors of light that when added together produce white light
Dye-a molecule that absorbs some light wavelengths and reflects or transmits others
Pigment-a colored material that absorbs certain colors and reflects or transmits other
colors
Primary pigment-a pigment that absorbs only one color from white light
Secondary pigment-a pigment that absorbs two primary colors from white light and
reflects one
Thin-film interference-light interference caused by reflection from the front and back
surface of a thin layer of liquid or solid
Polarized-light consisting of waves that vibrate on a specific plane
Regular reflection-reflection off a smooth surface, such as a mirror, where light is
reflected back to the observer in parallel beams, producing a clear image
Diffuse reflection-scattered, fuzzy reflection from a rough surface where light is
randomly reflected
Angle of refraction-angle the refracted ray makes with the normal to the surface
Optically dense-materials with larger indices of refraction with respect to other materials
Snell’s law-ratio of the sine of the angle of incidence to the sine of the angle of refraction
is a constant
Index of refraction-ratio of the speed of light in a vacuum to its speed in a material
Total internal reflection-occurs when light is incident on the boundary to a less optically
dense medium at an angle so large there is no refracted ray
Critical angle-incident angle unique to a substance that causes the refracted ray to lie
along the boundary of the substance
Dispersion-variation of the speed of light through matter resulting in separation of light
into a spectrum
Plane mirror-flat, smooth surface that reflects light rays by regular reflection, not by
diffuse reflection. Forms a virtual, erect image the same size as the object and the same
distance behind the mirror as the object is in front
Object-source of diverging light rays; may be luminous or illuminated
Image-reproduction of object formed with mirrors or lenses
Virtual image-point from which light rays appear to diverge without actually doing so
Erect image-mirror image that points in the same direction as the reflected object
Concave mirror-mirror that reflects light from its inwardly curved surface and produces
either inverted, real images or upright, virtual images
Principal axis-straight line perpendicular to the surface of a spherical mirror at its center.
Line perpendicular to the plane of a lens passing through its center
Focal point-point where parallel light rays converge or appear to diverge after reflecting
from a mirror or refracting from a lens
Focal length-distance from the focal point to the mirror along the principal axis
Real image-optical image formed when light rays converge and pass through the image,
producing an image that can be viewed on paper or projected onto a screen
Lens/mirror equation-1/f=1/di+1/do, where f is the focal length, di is the image distance,
and do is the object distance
Magnification-optical enlargement of an object; the ratio of the size of the image to the
size of the object
Spherical aberration-image defect of the spherical mirror that does not allow parallel light
rays far from the principal axis to converge at the focal point
Convex mirror-spherical mirror that reflects light from its outer surface and produces
virtual, reduced, upright images
Lens-transparent optical device, with a larger refractive index than air, used to converge
or diverge light
Convex lens-converging lens, thinner at its outer edge than at its center
Concave lens-diverging lens, thicker at its outer edge than at its center
Chromatic aberration-variation in focal length of a lens with the wavelength of light
Achromatic lens-lens for which all light colors have the same focal length