![]() ![]() a candle flame, an incandescent lamp, a discharge lamp, a fluorescent lamp). daylight, moonlight, sunlight) or artificial light (e.g. Light source Any source of visible radiant energy such as natural light (e.g. Solar light Light from the sun or having identical properties as the sun. Light reflex See corneal reflex pupil light reflex. Quantity of light Product of luminous flux and its duration. See analyser angle of polarization dichroic crystal polarizing lens polarizer Wollaston prism vectogram. tourmaline crystals, polarizing material such as Polaroid, Nicol prism, etc.). Polarized light can be obtained by using a polarizer (e.g. Polarized light is composed of transverse wave motions in only one direction, called the plane of vibration. ![]() Polarized light Ordinary light is composed of transverse wave motions uniform in all directions in a plane perpendicular to its direction of propagation. ![]() homocentric bundle of rays homocentric pencil of rays. The ray passing through the centre of the aperture is the chief ray. A pencil of light may be convergent, divergent or parallel. Pencil of light A narrow cone of light rays coming from a point source or from any one point on a broad source after passing through a limiting aperture. Natural light Light received from the sun and the sky. Monochromatic light Light consisting of a single wavelength or, more usually, of a narrow band of wavelengths (a few nanometres). The filament is heated and photons are released. tungsten) enclosed in a sealed oxygen-free glass bulb. An electrical current passes through a thin filament (e.g. Incandescent light Light emitted by incandescence as in an incandescent lamp. Idioretinal light A visual sensation occurring in total darkness that is attributed to spontaneous nervous impulses in the neurons of the visual pathway. Examples: mercury vapour lamp, neon and argon lamps, sodium vapour lamp, xenon flash lamp.įrequency of light See hertz electromagnetic spectrum wavelength. Electricity excites a gas that produces ultraviolet light, which in turn causes a phosphor coating on the inner surface of the fluorescent tube to fluoresce and emit visible light. See diffusion extended source.įluorescent light Light emitted by fluorescence as in a fluorescent lamp. Illumination is thus relatively uniform with a minimum of shadows. Cold light is free of infrared.Ĭompound light Light composed of more than one wavelength.ĭiffuse light Light coming from an extended source and having no predominant directional component. See pencil of light.Ĭold light Any visible light emitted by a process other than incandescence such as lasers, glow worms, certain chemical reactions, etc. See coherent sources infrared absorptive lens spectroscope electromagnetic spectrum visible spectrum Table C4 quantum theory wave theory ultraviolet wavelength.Īchromatic light See achromatic light stimulus.Īrtificial light Any light other than natural light.īeam of light A collection of pencils arising from an extended source or object. The borders of this band are not precise but beyond these radiations the visual efficacy of any wavelength becomes very low indeed (less than 10 −25). This band is called the visible spectrum or visible light. The radiations that give rise to the sensation of vision are comprised within the wavelength band 380-780 nm. Electromagnetic vibration capable of stimulating the receptors of the retina and of producing a visual sensation. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |