OPTICS AND WAVE | |
Acoustic shielding: | A sound barrier that prevents the transmission of acoustic energy. |
Adiabatic: | Any change in which there is no gain or loss of heat. |
Bar: | A unit of pressure, equal to 105 Pascals. |
Acoustics: | The science of the production, transmission and effects of sound. |
Afocal lens: | A lens of zero convergent power, whose focal points are infinitely distant. |
Albedo: | The fraction of the total light incident on a reflecting surface, especially a celestial body, which is reflected back in all directions. |
Amplitude: | The maximum absolute value attained by the disturbance of a wave or by any quantity that varies periodically. |
Angle of contact: | The angle between tangents to the liquid surface and the solid surface inside the liquid, both the tangents drawn at the point of contact. |
Angle of incidence: | The angle between the incident ray and the normal. |
Angle of reflection: | The angle between the reflected ray and the normal. |
Angle of refraction: | The angle between the refracted ray and the normal. |
Angle of repose: | The angle of inclination of a plane with the horizontal such that a body placed on the plane is at the verge of sliding. |
Angstrom: | A unit of length, 1 = 10-10 m. |
Beat: | A phenomenon of the periodic variation in the intensity of sound due to superposition of waves differing slightly in frequency. |
Brewster's law: | States that the refractive index of a material is equal to the tangent of the polarizing angle for the material. |
Candela: | The S.I. unit of luminous intensity defined as the luminous intensity in a given direction of a source that emits monochromatic photons of frequency 540 x 1012 Hz & has a radiant intensity in that direction of 1/683 W/sr |
Chromatic aberration: | An optical lens defect causing color fringes, because the lens brings different colors of light to focus at different points. |
Critical angle: | The angle of incidence in a denser medium for which angle of refraction is . |
Cyclotron: | A device used to accelerate the charged particles. |
Decibel: | Unit of sound level, if P1 & P2 are two amounts of power, the first is said to be n decibels greater, where n = 10 log10 (P1/P2) |
Diffraction: | The bending of light around the corners of an object. |
Dioptre: | Unit of power of a lens. |
Dispersion: | The splitting of white light into its component colors. |
Doppler Effect: | The apparent change in the frequency of a wave due to relative motion between the source and the observer. |
Fermat's principle: | An electromagnetic wave takes a path that involves the least time when propagating between two points. |
Focus: | The point to which rays that are initially parallel to the axis of a lens or mirror are converged or from which they appear to diverge. |
Fraunhoffer lines: | The dark lines in the spectrum of sun. |
Frequency: | The number of oscillations completed in 1 second by an oscillating body. |
Fundamental frequency: | The lowest frequency at which a system vibrates freely. |
Hertz: | The unit of frequency, also known as cycles per second. |
Huygens'principle: | Each point on a light wavefront can be regarded as a source of secondary waves, the envelope of these secondary waves determining the position of the wavefront at a later time. |
Infrasonic: | Sound waves of frequency less than 20 Hz, below the range of human hearing. |
Interference: | The redistribution of energy due to superposition of waves from coherent sources, resulting in alternate light and dark bands. |
Light-year: | The distance traveled by light through empty space in one year, it is equal to 9.46 x 1012 km. |
Longitudinal strain: | The ratio of change in length of a body to its initial length. |
Longitudinal wave: | The particles of the medium oscillate in the direction of propagation of the wave. |
Lyman series: | A group of lines in the ultraviolet region in the spectrum of hydrogen. |
Magnetic wave: | The spread of magnetization from a small portion of a substance where an abrupt change in the magnetic field has taken place. |
Magnification: | The ratio of the size of the image to the size of the object. |
Malus law: | The intensity of the light transmitted from the analyzer varies directly as the square of the cosine of the angle between the plane of transmission of analyzer and polarizer. |
Mechanical wave: | The waves, which need a material medium for their propagation, e.g., Sound waves. |
Megahertz: | Unit of frequency, equal to 106 hertz. |
Monochromatic light: | Consisting of single wavelength. |
Natural frequency: | The frequency, with which a system oscillates in the absence of external forces, it depends on the size, composition, and shape of the object. |
Optical fiber: | A long, thin thread of fused silica, used to transmit light, based on total internal reflection. |
Oscillatory motion: | The to and fro motion of a body about its mean position. |
Polaroid or polarizer: | A device that produces polarized light. |
Period of oscillation: | The time required for one complete oscillation. |
Periodic motion: | The motion which repeats itself after regular intervals of time. |
Progressive wave: | A wave which transfers energy from one part of a medium to another. |
Radiation: | The emission and propagation of waves transmitting energy through space or through some medium. |
Rarefaction: | A part of a longitudinal wave in which the density of the particles of the medium is less than the normal density. |
Real image: | An image which can be projected on a screen. |
Reflection: | The bouncing back of a wave from a boundary. |
Refraction: | The bending of light from its straight line path when it travels from one medium to another. |
Refractive index: | The ratio of speed of light in vacuum to that in the medium. |
Resolving power: | A quantitative measure of the ability of an optical instrument to produce separable images of different points of an object. |
Resonance: | When the frequency of an external force matches the natural frequency of the body then the body oscillates with large amplitude. |
Reverberation: | The prolongation of sound at a given point after direct reception from the source has ceased, it is due to reflections from the boundary surfaces. |
Snell's law: | The ratio of sin i to sin r is a constant and is equal to the refractive index of the second medium with respect to the first. |
Sonic boom: | Sound waves that pile up into a shock wave when a source is traveling at or faster than the speed of sound. |
Standing waves: | The waves formed due to superposition of two waves of same frequency and traveling in opposite directions with same speed. |
Total internal reflection: | Condition where all light is reflected back from a boundary between materials; occurs when light travels from denser to rarer medium and angle of incidence is greater than the critical angle. |
Transverse wave: | A wave in which the particles of the medium oscillate in a direction perpendicular of the direction of propagation of wave. |
Trough: | The point of maximum negative displacement on a transverse wave. |
Ultrasonic Sound: | Sound waves of frequencies above 20,000Hz. |
Unpolarized light: | Light consisting of transverse waves vibrating in all possible random directions. |
Vibration: | A back and forth motion that repeats itself. |
Virtual image: | An image formed when the reflected or refracted light rays appear to meet; this image cannot be projected on a screen. |
Wave motion: | The movement of a disturbance from one part of a medium to another involving the transfer of energy but not the transfer of matter. |
Wave period: | The time required for two successive crests or other successive parts of the wave to pass a given point. |
Wave velocity: | The distance traveled by a wave in one second. |
Wavelength: | The distance between the two nearest points on a wave, which are in the same phase or the distance between two adjacent crests or two adjacent troughs. |
Jumat, 06 Januari 2012
physics Term - optic and wave
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