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Light & Optical syst

Grade 8 Science

light The form of energy we can see.
radiant energy Energy transfered or transmitted as waves or rays in all directions
artificial light source A human made source of light
Incandescence The emission of visible light by a hot object
fluorescence The process in which high energy, invisible ultravioletlight is absorbed by the particles of an object, which then emits some of this energy as visible light, causing the object to glow
phosphorescence The persiistent emission of light following exposure to and removal of a source of radiation
chemiluminescence The emission of light resulting from chemical action and not involving heat
bioluminescence The emission of light produced by chemical reactions inside it's body to produce light
luminous Giving off its own light
transparent Allowing light to pass through
translucent Allowing some light to pass through. The light, however, is scattered from it's straight path
opaque Not allowing any light to pass through
Reflection The casting back of light from a surface
Angle of incident In optics, the angle between the incident ray and the normal
plane mirror A mirror having a flat surface
Law of reflection The two main predictible behaviours of reflected light: 1. The angle of incidence is equal to the angle of reflection. 2. The incident ray, the normal, and the reflected ray are always in the same plane.
Convex mirrors Mirrors that buldge out
Concave mirrors Mirrors that are caved in
Virtual image An image located where reflected rays only seem to originate
Refraction The bending of light when it travels form one medium to another
Angle of refraction In optics, the angle between the normal and the reflected ray
Lens A curved piece of transparent material, usually glass or plastic. Light rays bend as they pass through a lens.
Double convex lens Double convex is thicker in the middle than around the edges. This causes the refracting light rays to come together ,or converge.
Double concave lens Is thinner and flatter in the middle then around the edges. Light passing through the thicker, more curved areasof lens will bend more then light passing through flatter edges.
Retina A light sensitive area at the back of your eye
Near- Sighted People who have trouble seeing distant objects
Far- Sighted Have trouble seeing objects that areclose to them
Diaphram Is a device that controls the opening of the lens or optical system.
Aperature The opening of a lens or optical system.
Shutter In a camera,a device that opens the aperature to allow light to reach the film; can let more light reach the film by staying open longer
Optic Nerve The nerve that conects the eye to the brain
Blind Spot The point where the optic nerve enters the retina; has no light-sensing cells
Prisms In binoculars, glass blocks serving as plane mirrors; allow binoculars to be made shorter than telescopes
Soaler spectrum The patterns of colors in sunlight: red, orange, yellow, green, blue, indigo, and violet
Rod cell In the retina of the eye, a cylinder-like cell that detects the presence of light
Cone cell In the retina of the eye, a cone-shaped cell that detects color
Color Blindness A condition in which people have difficulty distinguidhing between some colors
Crests The high part of a wave
troughs The low part of a wave, between crests
wavelength The distance from crest to crest, or from trough to trough, of a wave of light as it travels through space; also used to describe the distance from crest to crest, or from trough to trough, of a water wave
amplitude In a wave the height of the crest or the depth of the trough
frequency The number of entire cycles completed by a vibrating object in a unit of time; usually given in cycles per second, or hertz
Laserlight A device for amplifying light to produce an intense, narrow, beam; used in computer printers, surgical procedures, and other applications. The term stand s for light amplication by the stimulated emmision of radiation
Incoherent light Refering to light, having many different wavelength but the waves are not lined uP
Coherent light Refering to light, having only one wavelength, with all waves lined up in a similar pattern
Electromagnetic spectrum The arrangement by wavelength of the different forms of electtro magnetic radiation, including visible light energy
Ultraviolet Light Radiation lying in the ultraviolet range, wavelengths shorter then light but longer than xrays
Xrays Electromagnetic radiation having a very short wavelength; can penetrate substances such as skin and muscle
Gamma Rays The rays having the shortest frequency and highest energy of all radiant waves in the electromagnetic spectrum; Gamma rays come from nuclear reactions
Angle of reflection In optics, the angle between the normal and the reflected ray
Created by: nawolskim