भौतिक विज्ञान (परिभाषा ) शब्दावली - 2

केल्विन पैमाना	Kelvin scale	The scale of temperature having a single fixed point, the temperature of the triple point of water, which is assigned the value 273.16 oK.
किलोग्राम	kilogram	A unit of mass in the metric system; one of the seven fundamental units.
किलोवाट घण्टा	kilowatt hour	A unit of electric energy equal to 3.6 x 106 w s.
गतिज ऊर्जा	kinetic energy	Energy possessed by an object because of its motion.
गतिज सिद्धान्त	kinetic theory	The molecules of matter are continuously in motion and the collisions between molecules are perfectly elastic.
किरचाफ का प्रथम नियम	Kirchhoff's first law	The algebraic sum of the currents at any circuit junction is equal to zero.
किरचाफ का द्वितीय नियम	Kirchhoff's second law	The algebraic sum of all changes in potential occurring around any loop in a circuit equals zero.
लेजर	laser	An acronym for light amplification by stimulated emission of radiation.
नियम	law	A statement that describes a natural phenomenon; a principle.
	law of conservation of baryons	When a baryon decays or reacts with another particle, the number of baryons is the same on both sides of the equation.
ऊर्जा संरक्षण का नियम	law of conservation of energy	The total quantity of energy in a closed system is constant.
	law of conservation of hypercharge	Hypercharge is conserved in strong and electromagnetic interactions, but not in weak interactions.
	law of conservation of leptons	In a reaction involving leptons, the arithmetic sum of the lepton numbers is the same on each side of the equation.
यांत्रिक ऊर्जा के संरक्षण का नियम	law of conservation of mechanical energy	The sum of the potential and kinetic energies of an ideal energy system is constant.
संवेग संरक्षण का नियम	law of conservation of momentum	When no net external forces are acting on an object, the total vector momentum of the object remains constant.
	law of entropy	A natural process always takes place in such a direction as to increase the entropy of the universe.
उष्मा विनिमय का नियम	law of heat exchange	In any heat transfer system, the heat lost by hot materials equals the heat gained by cold materials .
लेंज का नियम	Lenz's law	An induced current is in such a direction that its magnetic property opposes the change by which the current is induced.
	lepton	A subatomic particle with a small rest mass, e.g., the electron. line of flux. A line so drawn that a tangent to it at any point indicates the direction of the magnetic field.
बल रेखा	line of force	A line so drawn that a tangent to it at any point indicates the direction of the electric field.
रेखीय स्पेक्ट्रम	line spectrum	A spectrum consisting of monochromatic slit images having wavelengths characteristic of the atoms present in the source.
रेखीय त्वरक	linear accelerator	A device for accelerating particles in a straight line through many stages of small potential difference.
द्रवीकरण	liquefaction	The change to the liquid phase. The condensation of a gas to a liquid.
लीटर	liter	A special name for the cubic decimeter. Symbol: L.
अनुदैर्ध्य तरंग	longitudinal wave	A wave in which the vibrations are parallel to the direction of propagation of the wave.
	loop	A midpoint of a vibrating segment of a standing wave.
	loudness	The sensation that depends principally on the intensity of sound waves reaching the ear.
	lumen	The unit of luminous flux; the luminous flux on a unit surface all points of which are at unit distance from a point source of one candle:
	luminous	Visible because of the light emitted by its oscillating particles.
	luminous flux	The part of the total energy radiated per unit of time from a luminous source that is capable of producing the sensation of sight.
यंत्र	machine	A device that multiplies force at the expense of distance or that multiplies distance at the expense of force.
चुम्बकीय क्षेत्र	magnetic field	A region in which a magnetic force can be detected.
चुम्बकीय क्षेत्र की तीव्रता	magnetic field intensity	The force exerted by a magnetic field on a unit N pole situated in the field.
चुम्बकीय फ्लक्स	magnetic flux	Lines of flux through a region of a magnetic field, considered collectively.
	magnetic flux density	The magnetic flux through a unit area normal to the magnetic field; also called magnetic induction.
चुम्बकीय बल	magnetic force	A force associated with motion of electric charges.
	magnetosphere	A region of the upper atmosphere in which the motion of charged particles is governed primarily by the magnetic field of the earth.
आवर्धन	magnification	The ratio of the image distance to the object distance; the ratio of the image size to the object size.
	malleability	The property of a metal that enables it to be hammered or rolled into sheets.
द्रब्यमान	mass	A measure of the quantity of matter; a fundamental physical quantity.
द्रब्य घनत्व	mass density	Mass per unit volume of a substance.
	mass number	(1) The sum of the number of protons and neutrons in the nucleus of an atom. (2)
	mass spectrograph	Instrument used to determine the mass of ionized particles.
पदार्थ	matter	Anything that has the properties of mass and inertia.
द्रब्य तरंगें	matter wave	A property of matter that is directly proportional to Planck's constant and inversely proportional to mass and velocity.
उष्मा का यांत्रिक तुल्यांक	mechanical equivalent of heat	The conversion factor that relates heat units to work units; 4.19 j/cal.
यांत्रिक तरंग	mechanical wave	A wave that originates in the displacement of a portion of an elastic medium from its normal position, causing it to oscillate about an equilibrium position.
माध्यम	medium	Any region through which a wave disturbance propagates. Mechanical waves require a matter medium. Electromagnetic waves propagate through a vacuum and various matter media.
गलनांक	melting point	The temperature at which a solid changes to a liquid.
	meniscus	The crescent-shaped surface at the edge of a liquid column.
	meson	A subatomic particle with a rest mass intermediate between that of a lepton and a baryon; the carrier of the strong interaction.
मीटर	meter	A unit of length in the metric system equivalent to 1,650,763.73 wave-lengths of the orange-red light emitted by krypton-86. One of the seven fundamental units of measure.
मेट्रिक प्रणाली	metric system	A system of measurement that is based on decimal multiples and subdivisions.
मंदक	moderator	A material that slows down neutrons .
मोल	mole	Amount of substance containing the Avogadro number of particles such as atoms, molecules, ions, electrons etc. It is 6.02 X 1023 particles.
अणु	molecule	The smallest chemical species of a substance that is capable of stable independent existence.
संवेग	momentum	The product of the mass and velocity of a moving body.
एकवर्णीय प्रकाश	monochromatic light	Light composed of a single color.
अन्योन्य प्रेरण	mutual inductance	The ratio of the induced emf in one circuit to the rate of change of current in the coil of another circuit.
	neutral weak current	A subatomic reaction in which leptons collide without change in the charges of the colliding particles .
न्यूरान	neutron	A neutral subatomic particle having a mass of 1.674943 x 10–27 kg.
न्यूटन	newton	The unit of force; a derived unit having the dimensions kg m/s2. The force required to accelerate a one-kilogram mass at a rate of one meter per second each second.
न्यूटन का गति का प्रथम नियम	Newton's first law of motion	A body at rest or in uniform motion in a straight line will remain at rest or in the same uniform motion unless acted upon by an external force; also called the law of inertia.
न्यूटन का सार्वत्रिक गुरुत्व का नियम	Newton's law of universal gravitation	The force of attraction between any two particles of matter in the universe is directly proportional to the product of their masses and inversely proportional to the square of the distance between their centers of mass.
न्यूटन का गति का द्वितीय नियम	Newton's second law of motion	The acceleration of a body is directly proportional to the net force exerted on the body, is inversely proportional to the mass of the body, and has the same direction as the net force; also called the law of acceleration.
न्यूटन का गति का तृतीय नियम	Newton's third law of motion	If one body exerts a force on a second body, then the second body exerts a force equal in magnitude and opposite in direction on the first body; also called the law of interaction.
	node	A point of no disturbance of a standing wave.
	noise	Sound produced by irregular vibrations in matter which is unpleasant to the listener.
	noninertial frame of reference	An accelerating frame of reference in which Newton's first law of motion does not hold true.
अभिलम्ब	normal	A line drawn perpendicular to a line or surface.
	N-type germanium	"Electron-rich" germanium consisting of equal numbers of free electrons and bound positive charges so that the net charge is zero.
नाभिकीय बंधन ऊर्जा	nuclear binding force	The force that acts within the small distances between nucleons .
नाभिकीय परिवर्तन	nuclear change	A change in the identity of atomic nuclei.
	nuclear mass defect	The arithmetic difference between the mass of a nucleus and the larger sum of its uncombined constituent particles.
नाभिकीय भट्ठी/रिएक्टर	nuclear reactor	A device in which the controlled fission of certain substances is used to produce new substances and energy.
	nucleon	A proton or neutron in the nucleus of an atom. (nucleus) The positively charged dense central part of an atom.
	nuclide	An atom of a particular mass and of a particular element.
अष्टक	octave	The interval between a given musical tone and one with double or half the frequency.
ओम	ohm	The unit of electric resistance; one volt per ampere.
ओम का नियम	Ohm's law	The ratio of the emf applied to a closed circuit to the current in the circuit is a constant.
प्रकाशीय केन्द्र	optical center	The point in a thin lens through which the secondary axes pass.
	optical density	A property of a transparent material that is a measure of the speed of light through it.
कक्षक	orbital	The probability pattern of position of an electron about the nucleus of an atom.
	order of magnitude	A numerical approximation to the nearest power of ten.
	ordinate	The value corresponding to the vertical distance of a point on a graph from the X axis. The Y coordinate.
	oscilloscope	A cathode-ray tube with associated electronic circuits that enable external voltages to deflect the electron beam of the cathode-ray tube simultaneously along both horizontal and vertical axes.
समान्तर परिपथ	parallel circuit	An electric circuit in which two or more components connected across two common points in the circuit so as to provide separate conducting paths for the current.
समान्तर चतुर्भुज विधि	parallelogram method	The graphic method of finding the resultant of two vectors that do not act along a straight line.
	paramagnetism	The property of a substance by which it is feebly attracted by a strong magnet.
दोलक	pendulum	A body suspended so that it can swing back and forth about an axis.
	penumbra	The partially illuminated part of a shadow.
काल	period	((1)) The time for one complete cycle, vibration, revolution, or oscillation. (2)
आवर्ती गती	periodic motion	Motion repeated in each of a succession of equal time intervals.
	permeability	The property of a material by which it changes the flux density in a magnetic field from its value in air.
कला	phase	(1) A condition of matter. (2)
	phase angle	(1) Of any periodic function, the angle obtained by multiplying the phase by 360 if the angle is to be expressed in degrees, or by 2pi if in radians. (2)
	phasor	A representation of the concepts of magnitude and direction in a reference plane; a rotating vector.
	photoelastic	Pertaining to certain materials that become double refracting when strained.
प्रकाश वैद्युत प्रभाव	photoelectric effect	The emission of electrons by a substance when illuminated by electromagnetic radiation of sufficiently short wavelength.
प्रकाश वैद्युत इलेक्ट्रान	photoelectrons	Electrons emitted from a light-sensitive material when it is illuminated with light of sufficiently short wavelength.
प्रकाशमापी	photometer	An instrument comparing the intensity source with that of a standard source.
प्रकाशमिति	photometry	The quantitative measurement of visible radiation from light sources .
	photon	A quantum of light energy; the carrier of the electromagnetic interaction.
	photovoltaic effect	The generation of a potential difference across a P-N junction as a consequence of the absorption of incident light of appropriate frequency.
भौतिक परिवर्तन	physical change	A change in which the composition and identifying properties of a substance remain unchanged. physical quantity. A measurable aspect of the universe, such as length.
भौतिकी/भौतिक विज्ञान	physics	The science that deals with the relationships between matter and energy. The second half of life.
	piezoelectric effect	The property of certain natural and synthetic crystals to develop a potential difference between opposite surfaces when subjected to a mechanical stress, and conversely.
	pitch	The identification of a certain sound with a definite tone; depends on the frequency which the ear receives.
	pivot point	The point from which the lengths of all torque arms are measured.
प्लैंक नियतांक	Planck's constant	A fundamental constant in nature that determines what values are allowed for physical quantities in quantum mechanics; h = 6.63 x 10-34 j s.
प्लाज्मा	plasma	A gas that is capable of conducting an electric current.
प्लेट	plate	The anode of an electronic tube.
	P-N junction	The boundary between P and N-type materials in a semiconductor crystal.
ध्रुवित प्रकाश	polarized light	Light radiations in which the vibrations of all light waves present are confined to planes parallel to each other.
	polarizing angle	A particular angle of incidence at which polarization of reflected light is complete.
बहुवर्णी प्रकाश	polychromatic light	Light composed of several colors.
धन किरणें	positive rays	Rays coming through holes in a cathode on the side opposite the anode in a discharge tube. Positively charged ions.
विभवान्तर	potential difference	The work done per unit charge as a charge is moved between two points in an electric field.
स्थितिज ऊर्जा	potential energy	Energy that is the result of the position of an object. potential gradient. The change in potential per unit distance.
शक्ति/सामर्थ्य	power	The time rate of doing work. power factor. The cosine of the phase angle between current and voltage in an a-c circuit.
	precession	The motion that results from the application of a torque that tends to displace the axis of rotation of a rotating object.
	precision	The agreement between the numerical values of two or more measurements made in the same way and expressed in terms of deviation; the reproducibility of measured data.
दाब	pressure	Force per unit area.
प्राथमिक	primary	A transformer winding that carries current and normally induces a current in one or more secondary windings.
प्राथमिक सेल	primary cell	An electrochemical cell in which the reacting materials must be replaced after a given amount of energy has been supplied to the external circuit.
	primary colors	Colors in terms of which all other colors may be described or from which all other colors may be evolved by mixtures.
	primary pigments	The complements of the primary colors.
मुख्य अक्ष	principal axis	(1) A line drawn through the center of curvature and the vertex of a curved mirror. (2)
मुख्य नाभि	principal focus	A point at which rays parallel to the principal axis converge or from which they diverge after reflection or refraction.
सिद्धान्त	principle	See law.
	principle of parity	For every process in nature there is a mirror-image process which is indistinguishable from the original process.
	propagate	To travel through a material or space.
	propagation	The act of propagating. The action of traveling through a material or space.
गुण	property	A measurable aspect of matter, e.g., mass and inertia.
प्रोटान	proton	A positively charged subatomic particle having a mass of 1.6726485 x 10–27 kg and a charge equal and opposite to that of the electron.
	P-type germanium	"Hole-rich" germanium consisting of equal numbers of free positive holes and bound negative charges so that the net charge is zero.
	pulse	A single nonrepeated disturbance.
	quality	The property of sound waves that depends on the number of harmonics and their prominence.
क्वांतम	quantum	An elemental unit of energy; a photon of energy hf.
क्वांटम यांत्रिकी	quantum mechanics	The branch of physics that heals with the behavior of particles whose specific properties are given by quantum numbers.
क्वान्टम संख्या	quantum number	One of a set of notations used to characterize a discrete value that a quantized variable is allowed to assume.
क्वान्टम सिद्धान्त	quantum theory	A unifying theory based on the concept of the subdivision of radiant energy into discrete quanta (photons) and applied to the studies of structure at the atomic and molecular levels. (quark)
	quiescent	A steady-state condition. The operating condition of an electronic circuit when no input signal is applied.
रेडियन	radian	A unit of angular measurement. The angle that, when placed with its vertex at the center of a circle, subtends on the circumference an arc equal in length to the radius of the circle. Approximately 57.3o.
रेडियो तरंगें	radio waves	Also called Hertzian waves. Electromagnetic radiations produced by rapid reverses of current in a conductor.
रेडियोधर्मिता	radioactivity	The spontaneous breakdown of an atomic nucleus with the emission of particles and rays.
रेडियो समस्थानिक	radioisotope	An isotope of an element that is radioactive.
विरलन	rarefaction	The region of a longitudinal wave in which the vibrating particles are farther apart than their equilibrium distance .
किरण	ray	A single line of light from a luminous point. A line showing the direction of propagation of light.
प्रतिघात	reactance	The nonresistive opposition to current in an a-c circuit.
	reaction motor	A heat engine whose acceleration is produced by the thrust of exhaust gases.
वास्तविक प्रतिविम्ब	real image	An image formed by actual rays of light.
दिष्टकारी	rectifier	A device for changing alternating current to direct current.
	rectilinear propagation	Traveling in a straight line.
	reflectance	The ratio of the light reflected from a surface to the light falling on it, expressed in percentage.
परावर्तन	reflection	The return of a wave from the boundary of a medium.
अपवर्तन	refraction	The bending of a wave disturbance as it passes obliquely from one medium into another in which the disturbance has a different velocity.
	regelation	The melting of a substance under pressure and the refreezing after the pressure is released.
	regular reflection	Reflection from a polished surface in which scattering effects are negligible.
सापेक्षिक विपथन	relative deviation	Percentage average deviation of a set of measurements.
सापेक्षिक त्रुटि	relative error	Percentage absolute error of a set of measurements.
सापेक्षिक आर्द्रता	relative humidity	The ratio of the water vapor pressure in the atmosphere to the equilibrium vapor pressure at a given temperature.
	relativistic mass	The mass of an object in motion with respect to the observer.
	residual magnetism	Magnetism retained in a magnet after the magnetizing field has been removed.
प्रतिरोध	resistance	The ratio of the potential difference across a conductor to the magnitude of current in it.
प्रतिरोधकता	resistivity	A proportionality constant that relates the length and cross-sectional area of a given electric conductor to its resistance, at a given temperature.
	resolution of forces	The resolving of a single force into component forces acting in given directions on the same point.
अनुनाद	resonance	(1) The inducing of vibrations of a natural rate by a vibrating source having the same frequency. (2)
	rest mass	The mass of an object not in motion.
परिणामी	resultant	A vector representing the sum of several vector components. resultant force. The single force that has the same effect as two or more forces applied simultaneously at the same point.
	reverse bias	Voltage applied to a semiconductor P-N junction that reduces the electron current across the junction.
	rheostat	A variable resistance.
वर्गमूल माध्य धारा	root-mean-square {rms} current	The effective value of an alternating current; the square root of the mean of the instantaneous values squared.
घूर्णन गति	rotary motion	Motion of a body about an internal axis.
	rotational equilibrium	The state of a body in which the sum of all the clockwise torques in a given plane equals the sum of all the counterclockwise torques about a pivot point.
घूर्णीय जडत्व	rotational inertia	The property of a rotating object that resists changes in its angular velocity.
अदिश राशि	scalar quantity	A quantity that is completely specified by a magnitude.
	scientific notation	A positive number expressed in the form of M x 10n in which M is a number between 1 and 10 and n is an integral power of 10.
	scintillation counter	A device that counts the impacts of charged subatomic particles on a fluorescent screen by means of a photomultiplier tube.
सेकेण्ड	second	A unit of time; equivalent to 9,192,631,770 vibrations of cesium(1)13. One of the seven fundamental units of measure.
प्रकाश वैद्युत उत्सर्जन का द्वितीय नियम	second law of photoelectric emission	The kinetic energy of photoelectrons is independent of the intensity of the incident light.
उष्मागतिकी का द्वितीय नियम	second law of thermodynamics	It is not possible for an engine to transfer heat from one body to another at a higher temperature unless work is done on the engine.
द्वितीयक	secondary	A transformer output winding in which the current is due to inductive coupling with another winding called the primary.
	secondary axis	Any line other than the principal axis drawn through the center of curvature of a mirror or the optical center of a lens.
द्वितियक उत्सर्जन	secondary emission	Emission of electrons as a result of the bombardment of an electrode by high-velocity electrons.
	selectivity	The property of a tuned circuit that discriminates between signal voltages of different frequencies.
स्व-प्रेरणांक	self-inductance	The ratio of the induced emf across a coil to the rate of change of current in the coil.
श्रेणीक्रम परिपथ	series circuit	An electric circuit in which the components are arranged to provide a single conducting path for current.
श्रेणीक्रम अनुनाद	series resonance	A condition in which the impedance of a series circuit containing resistance, inductance, and capacitance is equal to the resistance of the circuit and the voltage across the circuit is in phase with the current.
	shear strain	The ratio of the amount of deformation of the side of a body to the length of the side.
	short circuit	An electric circuit through a negligible resistance that usually shunts a normal load and overloads the circuit.
	significant figures	Those digits in an observed quantity (measurement) that are known with certainty plus the first digit that is uncertain.
सरल आवर्त गति	simple harmonic motion	Motion in which the acceleration is proportional to the displacement from an equilibrium position and is directed toward that position.
सौर स्पेक्ट्रम	solar spectrum	The band of colors produced when sunlight is dispersed by a prism.
परिनालिका	solenoid	A long helical wound coil of insulated wire.
	solid state detector	A device used to detect the passage of charged subatomic particles by their crystal-distorting or ionizing effects on a nonconducting or nonconducting solid.
	solidification	The change of phase from a liquid to a solid.
	sonometer	A device, consisting of two or more wires or strings stretched over a sounding board, used for testing the frequency of strings and for showing how they vibrate.
ध्वनि	sound	The series of disturbances in matter to which the human ear is sensitive. Also similar disturbances in matter above and below the normal range of human hearing.
ध्वनि तीव्रता	sound intensity	The rate at which sound energy flows through a unit area.
	space charge	The negative charge in the space between the cathode and plate of a vacuum tube.
	spark chamber	A device used to detect the passage of charged subatomic particles by the light flashes they trigger.
विशिष्ट गुरुत्व	specific gravity	The ratio of the mass density of a substance to that of water.
विशिष्ट उष्मा	specific heat	The heat capacity of a material per unit mass.
	spectroscope	Optical instrument used for the study of spectra.
चाल	speed	Time rate of motion.
गोलीय विपथन	spherical aberration	The failure of parallel rays to meet at a single point on a spherical surface after reflection or refraction.
	spinthariscope	A device used to detect subatomic particles by the light flashes they produce on a zinc sulfide screen.
मानक दाब	standard pressure	The pressure exerted by 760 mm of mercury at O oC.
मानक ताप	standard temperature	OoC, 273oK.
	standing wave	The resultant of two wave trains of the same wavelength, frequency, and
आयाम	amplitude	traveling in opposite directions through the same medium .
स्थैतिक विद्युत	static electricity	Electricity at rest.
	steam point	The boiling point of water at standard atmospheric pressure.
स्टेरेडियन	steradian	The ratio of the intercepted surface area of a sphere to the square of the radius. A unit of solid angle.
भण्दारण सेल	storage cell	An electrochemical cell in which the reacting materials are regenerated by the use of a reverse current from an external source.
विकृति	strain	The relative amount of distortion produced in a body under stress.
प्रतिवाधा	stress	The distorting force per unit area.
	strong nuclear interaction	The interaction that holds the particles of the nucleus together and is independent of charge.
उर्ध्वपातन	sublimation	The change of a solid to a gaseous phase without passing through the liquid phase.
अतिचालकता	superconductivity	The condition of zero resistivity below the transition temperature of a substance.
अतिशीतलन	supercooling	The process of cooling a substance below its normal phase change point without a change of phase.
अध्यारोपण	superposition	Combining the displacements of two or more waves vectorially to produce a resultant displacement.
पृष्ट तनाव	surface tension	The tendency of a liquid surface to contract; the measure of this tendency in newtons per meter.
	sympathetic vibration	See resonance (1).
	synchrotron	A particle accelerator in which the oscillating frequency varies.
प्रौद्योगिकी	technology	The application of science to human needs and goals.
ताप	temperature	The physical quantity that is proportional to the average kinetic energy of translation of particles in matter.
अस्थायी चुम्बक	temporary magnet	A magnet produced by induction.
	tensile strength	The force required to break a rod or wire of unit cross-sectional area.
सिद्धान्त	theory	A plausible explanation of an observed event, supported experimentally and confirmed by experiments designed to test predictions based upon the explanation.
उष्मीय उर्जा	thermal energy	The total potential and kinetic energy associated with the random motions of the particles of a material.
तापायनिक उत्सर्जन	thermionic emission	The liberation of electrons from the surface of a hot body.
तापयुग्म	thermocouple	An electric circuit composed of two dissimilar metals whose junctions are maintained at different temperatures .
उष्मागतिकी	thermodynamics	Study of quantitative relationships between heat and other forms of energy.
तापवैद्युत प्रभाव	thermoelectric effect	The production of an electron current in a closed circuit consisting of two dissimilar metals as a result of the emf developed when the two junctions are maintained at different temperatures.
	thermonuclear reaction	Nuclear fusion.
प्रकाशवैद्युत उत्सर्जन का तृतीय नियम	third law of photoelectric emission	Within the region of effective frequencies, the maximum kinetic energy of photoelectrons varies directly with the difference between the frequency of the incident light and the cut-off frequency.
	thought experiment	An idealized experiment that cannot be performed under actual conditions.
	threshold of hearing	The intensity of the faintest sound audible to the average human ear, 10(1)6 w/cm2 at 103 hz.
	threshold of pain	For audible frequencies of sound, an intensity level above which pain results in the average human ear. Rock concert.
	tolerance	Degree of precision obtainable with a measuring instrument.
बलाघूर्ण	torque	Product of a force and the effective length of its torque arm.
	torque arm	The perpendicular distance between the line of action of the torque producing force and the axis of rotation.
पूर्ण परावर्तन	total reflection	The reflection of light at the boundary of two transparent media when the angle of incidence exceeds the critical angle.
ट्रान्सफार्मर	transformer	A device for changing an alternating voltage from one potential to another.
ट्रान्जिस्टर	transistor	A semiconductor device used as a substitute for vacuum tubes in electronic applications.
	transition temperature	A specific temperature at which the resistivity of some materials drops suddenly to zero.
	translational equilibrium	The state of a body in which there are no unbalanced forces acting on it.
	transuranium elements	Elements with atomic number greater than 92.
अनुप्रस्थ तरंग	transverse wave	A wave in which the vibrations are at right angles to the direction of propagation of the wave.
ट्रायोड	triode	Vacuum tube consisting of a plate, grid, and cathode.
	triple point	The single condition of temperature and pressure at which the solid, liquid, and vapor phases of a substance can coexist in stable equilibrium.
	trough	A region of downward displacement in a transverse wave.
स्वरित्र	tuning fork	A metal two-prong fork that produces a sound of a definite pitch.
पराश्रव्य परास	ultrasonic range	Vibrations in matter above 20,000 vibrations/second.
पराबैगनी प्रकाश	ultraviolet light	Electromagnetic radiations of shorter wavelength than visible light but longer than X rays.
	umbra	The part of a shadow from which all light rays are excluded.
अनिश्चितता का सिद्धान्त	uncertainty principle	It is impossible to specify simultaneously both the position of an object and its momentum.
एकिकृत क्षेत्र सिद्धान्त	unified field theory	The principle that all forces in the universe are part of a single concept.
इकाई चुम्बकीय द्विध्रुव	unit magnetic pole	One that repels an exactly similar pole placed one centimeter away with a force of one dyne.