Dictionary of Physics by Frantisek Fecko: N

nadir	nadir	The point opposite the zenith on the celestial sphere.
NAND gate	hradlo NAND	A logic gate in which the output is high unless all the inputs are high. NAND = NOT AND. This gate is simple to manufacture and can be used as a building block for many more complex devices.
near point	blízky bod	The nearest point at which the human eye can focus an object.
nebula (pl: nebulae)	hmlovina	An object in the universe that consists, for he most part, of interstellar gas and dust, and that cannot be resolved to individual stars. The gas atoms may have been ionised by ultraviolet radiation from nearby stars and light may be emitted as these ions interact with the free electrons in the gas.
negative charge	záporný náboj	One of the two forms in which charge occurs in nature, denoted with the minus sign (-). It has the sign as the charge of an electron.
neglect (v.)	zanedbávať, zanedbať (napr. odpor vzduchu)
net force	výsledná sila	One vector of force that has the same effect as all the forces (components) acted upon a body or particle.
neutrino	neutríno	Any one of a family of three light (probably massless) neutral leptons. They are the electron neutrino, the muon neutrino and the tau neutrino. Neutrinos have no charge, probably zero rest mass, and move at the speed of light.
neutron	neutrón	A neutral hadron that is stable in the atomic nucleus but decays into a proton, an electron, and an antineutrino with a mean life of 12 minutes outside the nucleus. Neutrons are found in all atomic nuclei except normal hydrogen.
neutron excess	neutrónový exces	Same as isotopic number.
neutron number	neutrónové číslo	Symbol N. The number of neutrons in an atomic nucleus of a particular nuclide.
neutron star	neutrónová hviezda	A compact stellar object that is supported against collapse under self-gravity by the degeneracy pressure of the neutrons of which it is primarily composed.
newton	Newton	Symbol N. The SI unit of force.
Newton’s law of gravitation	Newtonov gravitačný zákon	There is a force of attraction between any two massive particles in the universe. For any two point masses m₁ and m₂, separated by a distance r, the force of attraction F is given by F = Gm₁m₂/r², where G is the gravitational constant.
Newton’s laws of motion	Newtonove pohybové zákony	The three laws of motion on which Newtonian mechanics is based. (1) A body continues in a state of rest or uniform motion in a straight line unless it is acted upon by external forces. (2) The rate of change of momentum of a moving body is proportional to and in the same direction as the force acting on it, i.e. F = d(mv)/dt, where F is the applied force, v is the velocity of the body, and m its mass. If the mass remains constant, F = m.dv/dt or F = ma, where a is the acceleration. (3) (Action and reaction) If one body exerts a force on another, there is an equal and opposite force, called a reaction, exerted on the first body by the second.
Newton’s rings	Newtonove krúžky	Interference fringes formed by placing a slightly convex lens on a flat glass plate.
Newtonian mechanics	Newtonovská mechanika	The system of mechanics that relies on Newton’s laws of motion. It is applicable to bodies moving at speeds relative to the observer that are small compared to the speed of light.
nodal points	uzlové body	Two points on the axis of a system of lenses; if the incident ray passes through one, the emergent ray will pass through the other.
node	uzol	A point of minimal disturbance in a stationary-wave system.
noise	šum	An unwanted disturbance within a useful frequency band in a communication channel.
non-inertial frame of reference	neinerciálna vzťažná sústava	Any one of two or more coordinate systems where an observer stationary with respect to one of the coordinate systems would see an observer stationary with respect to any of the other coordinate systems as accelerating.
normal (n.)	normála	A line drawn at right angles to a surface.
normal Zeeman effect	normálny Zeemanov jav	Zeeman effect in which a single line is split into three if the field is perpendicular to the light path or two lines if the field is parallel to the light path.
NOT gate	hradlo NOT	Same as inverter.
nova	nova	A star that, over a period of only a few days, becomes 10³-10⁴ times brighter than it was.
n-type conductivity	vodivosť typu n	The conduction that occurs in an n-type semiconductor
n-type semiconductor	polovodič typu n	A semiconductor in which the charge is carried predominantly by electrons rather than holes.
nuclear chain reaction	jadrová reťazová reakcia	A chain reaction in which the succession depends on production and capture of neutrons. Thus, one nucleus of the isotope uranium-235 can disintegrate with the production of two or three neutrons, which cause similar fission of adjacent nuclei.
nuclear energy	jadrová energia	Energy obtained as a result of nuclear fission or nuclear fusion.
nuclear fission	jadrové štiepenie	A nuclear reaction in which a heavy nucleus (such as uranium) splits into two parts (fission products), which subsequently emit either two or three neutrons, releasing a quantity of energy equivalent to the difference between the rest mass of the neutrons and the fission products and that of the original nucleus.
nuclear fusion	jadrová syntéza	A type of nuclear reaction in which atomic nuclei of low atomic number fuse to form a heavier nucleus with the release of large amounts of energy.
nuclear magneton	jadrový magneton	Symbol μ_N. A unit of magnetic moment, μ_N = 5.05 x 10^-27 Am².
nuclear physics	jadrová fyzika	The branch of physics that concerns itself with the atomic nucleus, in particular the energy levels of nucleons within the nucleus, collisions between nuclei and the processes of radioactivity.
nuclear reaction	jadrová reakcia	Any reaction in which there is a change to an atomic nucleus.
nuclear reactor	jadrový reaktor	A device in which a nuclear fission chain reaction is sustained and controlled in order to produce nuclear energy, radioisotopes, or new nuclides.
nucleon	nukleón	A proton or a neutron.
nucleon number	nukleónové číslo	Symbol A. The number of nucleons in an atomic nucleus of a particular nuclide.
nucleus (of atom)	jadro (atómu)	The central core of an atom that contains most of its mass. It is positively charged and consists of one or more nucleons (protons or neutrons).
nuclide	nuklid	A type of atom as characterised by its atomic number and its neutron number.
objective	objektív	The lens or system of lenses nearest to the object being examined through an optical instrument.
observer	pozorovateľ
odd-even nucleus	nepárno-párne jadro	An atomic nucleus containing an odd number of protons and an even number of neutrons.
odd-odd nucleus	nepárno-nepárne jadro	An atomic nucleus containing an odd number of protons and an odd number of neutrons.
oersted	oersted	Symbol Oe. The unit of magnetic field strength in the c.g.s. electromagnetic system. 1 Oe = 10³/4π Am^-1.
ohm	ohm	Symbol Ω. The derived SI unit of electrical resistance.
Ohm’s law	Ohmov zákon	The ratio of the potential difference (U) between the ends of a conductor to the current (I) flowing through it is constant. The constant is the resistance of the conductor; i.e U = IR
ohmmeter	ohmmeter	Any direct-reading instrument for measuring the value of a resistance in ohms.
omnidirectional aerial	všesmerová anténa	An aerial which transmits or receives energy equally well in all directions.
opaque (adj.)	nepriehľadný	Describing a material which does not permit light (or some other specified form of electromagnetic radiation) to pass through it. Compare transparent; translucent.
operator	operátor	A mathematical symbol indicating that a specified operation should be carried out. Examples of operators: d/dt, Ö, Ĥ, etc.
optic nerve	zrakový nerv	Part of a human eye.
optical activity	optická aktivita	The ability of certain substances to rotate the plane of plane-polarised light as it passes through a crystal, liquid, or solution.
optical axis	optická os	The line passing through the optical centre and the centre of a curvature of a lens or spherical mirror.
optical centre	optický stred	The point at the geometrical centre of a lens through which a ray of light entering the lens passes without deviation.
optical fibre	optické vlákno	A solid glass or plastic fibre, typically thinner than the thickness of a human hair, that can transmit light. The light does not leave the fibre when it hits the edge, but passes along the fibre by the process of total internal reflection.
optical isomers (enantiomers)	optické antipódy (enantioméry)	Two forms of molecules each being the mirror image of the other.
optics	optika	The study of light and the phenomena associated with its generation, transmission, and detection.
OR gate	hradlo OR	A logic gate with two or more inputs that is high if any of the inputs is high.
orbit	orbita, obežná dráha	The path through space of one celestial body under the influence of the gravity of another.
orbital	orbital	A region of space in an atom or molecule that can be occupied by a maximum of two electrons.
orbital quantum number	vedľajšie kvantové číslo (orbitálové kvantové číslo)	Symbol l. The quantum number which governs the angular momentum of the electron. The possible values of l are (n-1), (n-2), … , 1, 0. Thus, in the first shell (n = 1) the electrons can only have angular momentum zero (l = 0). In the second shell (n = 2), the values of l can be 1 or 0, giving rise to two subshells of slightly different energy. In the third shell (n = 3) there are three subshells, with l = 2, 1, or 0. The subshells are denoted by letters s (l = 0), p (l = 1), d (l = 2), f (l = 3). See also atom
ordinary ray	riadny lúč	One of the two rays of double refraction, the one that obeys the normal laws of refraction. Compare extraordinary ray.
oscillation	kmitanie, kmitavý pohyb	A motion that repeats itself at regular intervals. The time taken for one complete oscillation is called the period, whilst the number of oscillations in one second is called the frequency.
oscillator	oscilátor	An electronic device that produces an alternating output of known frequency.
oscilloscope	osciloskop	See cathode-ray oscilloscope.
out of phase	nesfázované (prekladá sa ...ktoré nie sú vo fáze...)	Describing two oscillations that are not exactly in step with one another or that are exactly out of step with one another.
output	výstup
ozone layer	ozónová vrstva	A protective layer consisting of the gas ozone, O₃, 15 to 40 km above the earth’s surface. The ozone layer prevents harmful ultraviolet radiation reaching the earth’s surface.
pair production	produkcia páru, párová produkcia	The creation of an electron and positron from a photon in a strong electric field.
parallax	paralaxa	The angular displacement in the apparent position of a celestial body when observed from two different points.
parallel	rovnobežný
parallel circuits	paralelný obvod	A circuit in which the circuit elements are connected so that the current divides between them.
paramagnetism	paramagnetizmus	A weak form of magnetism found in some elements and molecules (such as O₂), causing these materials to have a relative permeability slightly greater than 1.
paraxial ray	paraxiálny lúč	A ray of light that falls on a reflecting or refracting surface close to and almost parallel to the axis.
parent	rodičovský nuklid, rodič	A nuclide from which some other nuclide (the daughter) is produced by radioactive decay.
parity	parita	Symbol P. The property of a wave function that determines its behaviour when all its spatial coordinates are reversed in direction, i.e. when x,y,z are replaced by -x,-y,-z.
parsec	parsek	Symbol pc. Acronym of parallax second. A unit of length used in astronomy. 1 pc = 3.0857 x 10¹⁶ m = 2.06 x 10⁵ AU.
particle	1. častica 2. hmotný bod (v mechanike)	1. (in physics) One of the fundamental components of matter. See elementary particle 2. (in mechanics) A hypothetical body that has mass but no physical extension. As it is regarded as having no volume, a particle is incapable of rotation and therefore can only have translational motion.
particle accelerator	urýchľovač častíc	An apparatus for increasing the kinetic energies of charged particles, used for research in nuclear and particle physics. See also cyclotron; linear accelerator.
particle physics	fyzika elementárnych častíc	The study of elementary particles.
pascal	pascal	Symbol Pa. The SI unit of pressure.
Pascal’s law	Pascalov zákon	In a confined fluid, externally applied pressure is transmitted uniformly in all directions.
passive device	pasívny prvok obvodu	An electronic device, such as a resistor, capacitor or inductor, that cannot amplify a current.
Pauli exclusion principle	Pauliho vylučovací princíp	The quantum-mechanical principle, applying to fermions but not to bosons, that no two identical particles in a system (such as electrons in an atom or quarks in a hadron) can posses an identical set of quantum numbers.
peak	vrch, vrchol, vlnove maximum
pendulum	kyvadlo	A system in which a point-like mass exhibits oscillatory motion. See also simple pendulum.
perfect vacuum	dokonalé vákuum	A vacuum that contains no atoms or molecules. This is unobtainable as all the materials that surround such a space have a finite vapour pressure.
pericynthion	pericyntium	The point in the orbit around the moon of a satellite launched from the earth that is nearest to the moon.
perigee	perigeum	For an object in orbit around the earth, the position in the orbit that is closest to the earth.
perihelion	perihélium	The point in the orbit of a planet, comet, or artificial satellite in solar orbit at which it is nearest to the sun.
period	perióda	Symbol T. The time taken to complete an orbit or oscillation. It is measured in second (s).
periodic motion	periodický pohyb	Any motion of a system that is continuously and identically repeated.
permeability	permeabilita	Symbol m. The ratio of the magnetic flux density (B) in a substance to the external field strength (H), i.e. m = B/H. The permeability of free space, m₀, is also called the magnetic constant and has the value 4p x 10^-7 H.m^-1 in SI units. The relative permeability of a substance, m_r, is given by m_r = m/m₀, and is therefore dimensionless.
permitivity	permitivita	Symbol e. The ratio of the electric displacement (D) in a medium to the electric field (E) producing it, i.e. e = D/E. If two charges Q₁ and Q₂ are separated by a distance r in a vacuum, the force between charges is given by F = Q₁Q₂/r²4pe₀. In this statement of Coulomb’s law using SI units, e₀ is called the absolute permittivity of free space, which is now known as electric constant. e₀ = 8.854 x 10^-12 Fm^-1. If the medium between the charges is anything other than a vacuum the equation becomes: F = Q₁Q₂/r²4pe and the force between the charges is reduced. e is the absolute permitivity of the new medium. The relative permitivity (e_r) of a medium is given by e_r = e/e₀.
perpetual motion	perpetuum mobile	The state of some hypothetical machine which, once set to motion, would continue to move for ever without any further energy input.
phase	fáza	1. Any one of the different arrangements in which the atoms/molecules of a certain substance may exist, as a gas, liquid, or as one or more solid forms (e.g. amorphous). 2. A measure of the stage that an oscillation has reached at a given instant, particularly when comparing two oscillations. Phase is usually expressed as an angle.
phase diagram	fázový diagram	A graph showing the relationship between solid, liquid, and gaseous phases over a range of conditions (e.g. temperature and prssure).
phase modulation	fázová modulácia	One of the types of modulation.
phase velocity	fázová rýchlosť	Symbol v_f. In a travelling wave, the speed at which a point of a given phase travels through a material (i.e. the speed of propagation of a travelling wave). v_f = lf, where l is the wavelength and f is the frequency.
phasor	fázor	A rotating vector that represents a sinusoidally varying quantity.
photoelectric effect	fotoelektrický jav	The liberation of electrons from a substance exposed to electromagnetic radiation. The effect is a quantum process in which the radiation is regarded as a stream of photons, each having an energy hf, where h is the Planck constant and f is the frequency of the radiation.
photoelectron	fotoelektrón	An electron emitted from a substance by irradiation as a result of the photoelectric effect.
photon	fotón	A particle with zero rest mass consisting of a quantum of electromagnetic radiation.
physical quantity	fyzikálna veličina
physics	fyzika	The study of the laws that determine the structure of the universe with reference to the matter and energy of which it consists. It is concerned not with chemical changes that occur but with the forces that exist between objects and the interrelationship between matter and energy.
piezoelectric effect	piezoelektrický jav	The generation of the potential difference across the opposite faces of certain nonconducting crystals as a result of the application of mechanical stress between these faces.
pinch effect	pinch-efekt	A magnetic attraction between parallel conductors carrying currents flowing in the same direction. It has been widely studied as a means of confining the hot plasma in a thermonuclear reactor.
pion, pi-meson	pión, pi-mezón	An elementary particle classified as a meson.
pipe	trubica
piston	piest	A round metal plate, usually with a flat surface, which moves up and down in a cylinder in response to pressure changes.
Planck constant	Planckova konštanta	h = 6.626176 x 10^-34 Js.
Planck’s radiation law	Planckov vyžarovací zákon	A law giving the distribution of energy radiated by a black body. The expression for the monochromatic specific intensity E_f is: E_f = 2hc^-2f³/(exp(hf/kT)-1), where h is the Planck constant, c is the speed of light, k is the Boltzmann constant, and T is the thermodynamic temperature.
plane angle	rovinný uhol
plane-polarised light	rovinne-polarizované svetlo	Light (electromagnetic wave) in which the electric (E) and magnetic (B) fields each oscillate in a single plane, perpendicular to one another and to the direction of light propagation. See also polarisation.
plane-polarised wave	rovinne-polarizovaná vlna	An electromagnetic wave in which the electric (E) and magnetic (B) fields each oscillate in a single plane, perpendicular to one another and to the direction of wave propagation. See also polarisation.
planet	planéta	A large (roughly spherical) celestial body, composed mainly of rock or gas, that revolves around a central astronomical body, usually a star.
plano-concave lens	ploskodutá šošovka	A type of a diverging lens.
plano-convex lens	ploskovypuklá šošovka	A type of a converging lens.
plasma	plazma	A highly ionised gas in which the number of free electrons is approximately equal to the number of positive ions.
plasticity	tvárnosť	The property of solids that causes them to change permanently in size or shape as a result of the application of a stress in excess of a certain value, called the yield point.
pn junction, PN junction	prechod PN	A junction between a p-type and n-type semiconductor.
point charge	bodový náboj	An abstraction used in physics denoting a charged particle or a body whose size and volume is neglected (it is regarded as dimensionless particle - point) and only its charge is taken into the consideration.
point defect	bodová porucha	Defect that consists either of a missing atom or ion creating a vacancy in the lattice, or an extra atom or iron between two normal lattice points creating an interstitial.
point-like mass	hmotný bod, bodová hmotnosť	(used with pendulum) A hypothetical body that has mass but no physical extension (i.e. no volume)
polar coordinate system	polárna súradnicová sústava	Coordinate system in two-dimensional space (plane) in which a point P is given in coordinates (r,j), where r is distance of P from the origin, and j is the angle between the x-axis and the radius vector OP.
polar coordinates	polárne súradnice	(r,j) - used in two-dimensional systems only.
polarisation	polarizácia	1. The process of confining the vibrations of the vector constituting a transverse wave to one direction. 2. The partial separation of electric charges in an insulator subjected to an electric field.
polarisation of light	polarizácia svetla	The process of confining the vibrations of the electric vector (E) of light waves to one direction.
pole	pól	1. The point on the surface of an object (e.g. a planet) at which the axis of rotation passes through that surface. 2. The region on the surface of a magnet at which the magnetic filed lines enter and leave the magnet.
porous pot	pórovitá stena
position vector	polohový vektor	Symbol r. If a point P has Cartesian coordinates (x,y,z) in a frame of reference with origin O, then r = OP, i.e. r = xi + yj + zk, where i, j, k are unit vectors along the three coordinate axes.
positive charge	kladný náboj	One of the two forms in which charge occurs in nature, denoted with the plus sign (+). It has the sign as the charge of a proton.
positive holes	kladné diery	See holes.
positron	pozitrón	The antiparticle of the electron.
potential	potenciál	Short for electric or gravitational potential.
potential barrier	potenciálna bariéra	A region containing a maximum of potential that prevents a particle on one side to the other side.
potential difference	napätie, rozdiel potenciálov	Symbol U. The potential difference between two points in an electric field or circuit is the difference in the values of the electric potentials at the two points, i.e. it is the work (W) done in moving unit charge (Q) from one point to the other. U = \|φ₁ - φ₂\| = W/Q.
potential energy	potenciálna energia	Symbol E_p. The energy possessed by an object or system as a result of its position or state.
potentiometer	potenciometer	The way of connecting a variable resistor in an electrical circuit so that we can have a continuous range of voltage from 0 to the total voltage.
pound	libra	Symbol lb. The unit of mass in the f.p.s. system of units. 1lb = 0.45359237 kg.
power	výkon	Symbol P. The rate at which work is done or energy transferred. P = dW/dt or P = dE/dt. In SI units it is measured in watts (W).
power factor (of the circuit)	účinník	cos φ, as in equation P = UIcos φ in an alternating-current circuit.
power of lens	optická mohutnosť šošovky
pressure	tlak	Symbol p. The force acting normally on unit area of a surface or the ratio of force to area. p = F/S. It is measured in pascals (Pa).
pressure energy	tlaková energia
pressure gauge	tlakomer	Any device used to measure pressure.
pressure law (Charles’ law of pressure)	Charlov zákon	For a fixed mass of an ideal gas held in a constant volume, the pressure is proportional to the absolute temperature; that is, the pressure divided by the absolute temperature is a constant, p/T = constant.
primary cell	primárny článok	A voltaic cell in which the chemical reaction producing the e.m.f. is not satisfactorily reversible and the cell cannot therefore be recharged by the application of a charging current. Compare secondary cell.
primary colour	primárna farba	Any one of a set of three coloured lights that can be mixed together to give the sensation of white light as well as approximating all the other colours of the spectrum. The set of primary colours most frequently used is red, green, and blue.
primary winding	primárne vinutie	The winding on the input side of a transformer or induction coil.
principal quantum number	hlavné kvantové číslo	Symbol n. The quantum number that gives the main energy level and has values 1, 2, 3, etc. (the higher the number, the further the electron from the nucleus). Traditionally, these levels, or the orbits corresponding to them, are referred to as shells and given the letters K, L, M, etc. The K-shell is the one nearest the nucleus. See also atom.
principle of superposition	princíp superpozície	The resultant displacement at any point in a region through which two waves of the same type pass is the algebraic sum of the displacements that the two would separately produce at that point. Both waves leave the region of superposition unaltered.
progressive wave	postupné vlnenie	A wave in which energy is transferred from one place to another by the vibrations.
prompt neutrons	okamžité neutróny
proton	protón	An elementary particle that is stable, bears a positive charge equal in magnitude to that of the electron
proton number	protónové číslo	Same as atomic number.
protostar	protohviezda	A cloud of gas, mostly hydrogen and helium, that is collapsing under its own gravitation and may eventually become hot enough at its centre for nuclear fusion to take place, leading to the formation of a star.
psi particle	častica psi	See ψ/J particle.
p-type conductivity	vodivosť typu p	The conduction that occurs in an p-type semiconductor
p-type semiconductor	polovodič typu p	A semiconductor in which the charge is carried predominantly by holes rather than electrons.
pulley	kladka, kladkostroj	One of the six simple machines.
pulsar	pulzar	A star that flashes with a well defined period. Pulsars are now recognised as neutron stars, and the flashing is caused by the interaction between the radiation from the neutron star and its magnetic field.
pupil	zornica	Part of a human eye
quantum (pl. quanta)	kvantum	The minimum amount by which certain properties, such as energy or angular momentum, of a system change.
quantum chromodynamics (QCD)	kvantová chromodynamika	A gauge theory that describes the strong interaction in terms of quarks and antiquarks and the exchange of massless gluons between them.
quantum electrodynamics (QED)	kvantová elektrodynamika	The study of the properties of electromagnetic radiation and the way in which it interacts with charged matter in terms of quantum mechanics.
quantum jump	kvantový skok, kvantový preskok	A change in a system (e.g. an atom) from one quantum state to another.
quantum mechanics	kvantová mechanika	A system of mechanics that was developed from quantum theory and is used to explain the properties of atoms and molecules.
quantum number	kvantové číslo	A number that represents the value of some quantity such as charge, which is conserved in certain types of interactions and which is only found in whole number multiples of some basic quantity. In an atom, each electron can be characterised by a set of four quantum numbers, as follows: (1) The principal quantum number (n) gives the main energy level and has values 1, 2, 3, etc. (the higher the number, the further the electron from the nucleus). Traditionally, these levels, or the orbits corresponding to them, are referred to as shells and given the letters K, L, M, etc. The K-shell is the one nearest the nucleus. (2) The orbital quantum number (l), which governs the angular momentum of the electron. The possible values of l are (n-1), (n-2), … , 1, 0. Thus, in the first shell (n = 1) the electrons can only have angular momentum zero (l = 0). In the second shell (n = 2), the values of l can be 1 or 0, giving rise to two subshells of slightly different energy. In the third shell (n = 3) there are three subshells, with l = 2, 1, or 0. The subshells are denoted by letters s (l = 0), p (l = 1), d (l = 2), f (l = 3). (3) The magnetic quantum number (m), which governs the energies of electrons in an external magnetic field. This can take values of +l, +(l-1), … , 1, 0, -1, … , -(l-1), -l. In an s-subshell (i.e. l = 0) the value of m = 0. In a p-subshell (l = 1), m can have values +1, 0, -1; i.e. there are three p-orbitals in the p-subshell, usually designated p_x, p_y, and p_z. (4) The spin quantum number (m_s), which gives the spin of the individual electrons and can have the values +½ or -½. According to the Pauli exclusion principle, no two electrons in the atom can have the same set of quantum numbers. The numbers define the quantum state of the electron, and explain how the electronic structures of atoms occur.
quantum state	kvantový stav	The state of a quantised system as described by its quantum numbers. For instance, the state of a hydrogen atom is described by the four quantum numbers n, l, m, s. In the ground state they have values 1, 0, 0, and ½ respectively.
quantum theory	kvantová teória	The theory that energy is absorbed or released in discrete, indivisible units called quanta.
quark	kvark	Any member of the fundamental family of particles from which all hadrons, including the proton and neutron, are made. Quarks are held together in hadrons by the strong nuclear force and come in six varieties called flavours (up, down, strange, charm, top, bottom).
quark confinement	kvarkové uväznenie	The hypothesis that free quarks can never be seen in isolation.
quasar	kvazar	Acronym of quasi-stellar object. An object that appears as a star when viewed through a telescope, but which has an unusually high red-shift. It is now believed that many quasars are in fact extremely distant galaxies.