gain (n.)

zisk

The ratio of the output amplitude (of potential difference or current) of an amplifier (or stage of an amplifier) to the corresponding input amplitude.

gain (v.) [energy]

získať [energiu]

galaxy

galaxia

A large volume of space containing millions of stars held together by gravity. Galaxies are surrounded by smaller, roughly spherical groupings of stars called globular clusters.

galaxy cluster

kopa galaxií

A group of galaxies containing many hundreds of members extending over a radius of up to a few megaparsecs.

Galilean relativity

Galileiho princíp relativity

The relativity principle as applied to Newton’s laws of motion, in which the motion of an object in one inertial reference frame could be computed from a knowledge of its motion in another inertial frame by the addition of the relative velocity of the two frames. See also Galilean transformations.

Galilean transformations

Galileiho transformácie

A set of equations for transforming the position and motion parameters from a frame of reference with origin at O and coordinates (x,y,z) to a frame origin at O’ and coordinates at (x’,y’,z’). They are:

x’ = x - vt

y’ = y

z’ = z

t’ = t

galvanic cell

galvanicky článok

Same as voltaic cell.

galvanometer

galvanometer

An instrument for detecting and measuring small electric currents.

gamma radiation

gama žiarenie

Electromagnetic radiation emitted by excited atomic nuclei during the process of passing to a lower excitation state. Gamma radiation ranges in wavelengths from about 10^-10 m to 10^-14 m.

gas

plyn

A state of matter in which the matter concerned occupies the whole of its container irrespective of its quantity.

gas constant

plynová konštanta

R = 8.314510 JK^-1mol^-1

gas equation

plynová rovnica

pV = nRT

gas laws

plynové zákony

Laws relating the temperature, pressure, and volume of an ideal gas. See Boyle’s law, Charles’ law, and the pressure law.

gas thermometer

plynový teplomer

A device for measuring temperature in which the working fluid is a gas.

gas-cooled reactor

plynom chladený reaktor

A nuclear reactor in which the coolant is a gas with an outlet temperature of about 350°C.

gate

1. hradlo

2. brána

1. An electronic circuit with a single output and one or more inputs; the output is a function of the input or inputs. See Logic gate.

2. The electrode in a field-effect transistor that controls the current through the channel.

gauge

merač, kalibračný prístroj

gauge boson

kalibračný bozón

A particle that is exchanged between two particles, carrying energy and momentum. This is the quantum mechanical interpretation of a force acting between the two particles.

The following table shows by exchange of what particles the forces of fundamental interactions act:

gauge theory

kalibračná teória

Any theory of interactions between elementary particles that exhibits properties associated with certain forms of symmetry.

Gauss’ law

Ostrogradského-Gaussova veta

The total electric flux (y) through any closed surface (S) is equal to the total charge (Q) enclosed by the surface divided by the permitivity of free space (e₀).

y = ƒE.dS = Q/e₀

Gay Lussac’s law

Gay-Lussacov zákon

See Charles’ law.

Geiger counter

Geiger-Müllerov počítač

A device, containing a Geiger-Müller tube, used to detect and measure ionising radiation.

Geiger-Müller tube

Geiger-Müllerova trubica

A device for detecting ionising radiation using the flow of current in a sample of low pressure gas.

Geissler tube

Geisslerova trubica

An early form of gas-discharge tube.

general theory of relativity

všeobecná teória relativity

The theory of 1915, in which A.Einstein extended his earlier work (special theory of relativity) to include accelerated systems.

generator

generátor

Any machine that converts mechanical power into electrical power.

geocentric universe

geocentrický vesmír

A view of the universe in which the earth is regarded as being at its centre.

geomagnetism

geomagnetizmus

The science concerned with the earth’s magnetic field.

geostationary orbit

geostacionárna orbita

A circular orbit over the Earth’s equator, moving in the same direction as the Earth’s rotation and with the same period, i.e. 23 hours 56 minutes 4.1 seconds.

geosynchronous orbit

geosynchrónna orbita

An orbit around the Earth with a period exactly equal to the earth’s period of rotation on its axis, i.e. 23 hours 56 minutes 4.1 seconds. If the orbit lies in the equatorial plane and is circular, it is called the geostationary orbit.

giant star

obrovitá hviezda

A very large star that is highly luminous. Lying above the main sequence on a Hertzsprung-Russel diagram, giant stars represent a late stage in stellar evolution.

Glashow-Weinberg-Salam model (GWS model)

GWS model

See electroweak theory.

globular cluster

guľová hviezdokopa

A roughly spherical grouping of a few hundred stars found in orbit around a galaxy.

glow discharge

tlejivý (elektrický) výboj

An electrical discharge that passes through a gas at low pressure and causes the gas to become luminous.

gluon

gluón

The gauge boson that is exchanged in the strong nuclear force, named as the glue that holds quarks together in a hadron.

gradient (grad)

gradient

Symbol grad. The operator

� = i δ/δx + j δ/δy + k δ/δz,

where i, j, and k are unit vectors in the x, y, and z directions.

gram

gram

Symbol g. Unit of mass.

1 g = 10^-3 kg.

grand unified theory (GUT)

veľká jednotná teória

A hypothetical unification of the electroweak force and strong nuclear force, and possibly gravity too.

gravitation

gravitácia

See Newton’s law of gravitation.

gravitational constant

gravitačná konštanta

G = 6.67259 x 10^-11 N.m².kg^-2

gravitational field

gravitačné pole

The region of space surrounding a body that has the property of mass. In this region any other body that has mass will experience a force of attraction.

gravitational interaction

gravitačná inerakcia

The weakest of the four fundamental interactions, some 10⁴⁰ times weaker than the electromagnetic interaction. The force that it generates acts between all bodies that have mass and the force is always attractive.

gravitational mass

gravitačná hmotnosť

Symbol m_g. Mass defined in terms of gravitational force it produces.

m_g = Fd²/MG,

where M is the mass of a standard body situated a distance d from the body of mass m_g, F is the gravitational force between them and G is the gravitational constant.

Compare inertial mass.

gravitational potential

gravitačný potenciál

Symbol V_g (also φ_g). The gravitational potential at a point is the work needed to bring a 1 kg of mass from infinity to that point. At a distance r from the centre of a body of mass M and radius R, if r is greater than R, the gravitational potential is

V_g = -GM/r,

where G is the gravitational constant.

gravitational shift

gravitačný posun

See redshift.

gravitational waves

gravitačné vlny

Waves propagated through a gravitational field.

graviton

gravitón

The hypothetical gauge boson responsible for gravity in a quantum theory of gravity.

gravity

gravitácia, gravitačná sila

The force of attraction between all objects dependent on their mass. Gravity is a weak force, so it is normally only noticeable when at least one of the masses is very large.

gray

gray

Symbol Gy. The SI unit of absorbed ionising radiation.

greenhouse effect

sklenníkový efekt

1. The effect within a greenhouse in which solar radiation mainly in the visible range of the spectrum passes through the glass roof and walls and is absorbed by the floor, earth, and contents, which re-emit the energy as infrared radiation. Because the infrared radiation cannot escape through the glass, the temperature inside the greenhouse rises.

2. A similar effect in which the Earth’s atmosphere behaves like the greenhouse and the surface of the Earth absorbs most of the solar radiation, re-emitting it as infrared radiation.

grid

mriežka

Short for control grid.

ground state

základný stav

The lowest stable energy state of a system, such as a molecule, atom, or nucleus. See energy level.

gyromagnetic ratio

gyromagnetický pomer

Symbol γ. The ratio of the angular momentum (L) of an atomic system to its magnetic moment (m),

γ = L/m.

hadron

hadron

Any of a class of subatomic particles that are influenced by the strong nuclear force. Hadrons can be subdivided into baryons and mesons. All hadrons are composed of particles called quarks held together by the strong nuclear force.

half cell

polčlánok

An electrode in contact with a solution of ions, forming part of a cell.

half-life

polčas rozpadu

The time required for half the original nuclides to decay.

half-thickness

polhrúbka

The thickness of a specified material that reduces the intensity of a beam of radiation to half its original value.

half-wave rectifier

jednocestný usmerňovač

A rectifier in which only every second half-wave is rectified, so that a pulsating current is produced

Hall effect

Hallov jav

The production of an e.m.f. within a conductor or semiconductor through which a current is flowing when there is a strong transverse magnetic field. The potential difference develops at right angles to both the current and the field.

Hall voltage

Hallovo napätie

Voltage produced by the Hall effect.

Hamiltonian

Hamiltonián, Hamiltonova funkcia

Symbol H. A function used to express the energy of a system in terms of its momentum (p) and positional coordinates (q)

H = Σ(p_e.dq_e/dt) - L,

where L is the Lagrangian.

For an isolated system it is the sum of its total kinetic (T) and potential (U) energies: H = T + U.

hard radiation

tvrdé žiarenie

Ionizing radiation of high penetrating power, usually gamma rays or short-wavelength X-rays.

harmonic (n.)

harmonická, harmonická frrekvencia

An oscillation having a frequency that is a simple multiple of a fundamental sinusoidal oscillation. The fundamental frequency of a sinusoidal oscillation is usually called the first harmonic. The second harmonic has a frequency twice that of the fundamental and so on.

harmonic motion

harmonický pohyb

Short for simple harmonic motion.

Hawking process

Hawkingov proces

Emission of particles by a black hole as a result of quantum-mechanical effects. The gravitational field of the black hole causes production of particle-antiparticle pairs in the vicinity of the event horizon. One member of each pair (either the particle or the antiparticle) falls into the black hole, while the other escapes. To an external observer, it appears that the black hole is emitting radiation (Hawking radiation).

Hawking radiation

Hawkingovo žiarenie

Electromagnetic radiation arising from the creation of electron-positron pairs in the intense gravitational field of a black hole with only one member of the pair falling into the black hole. See Hawking process.

heat

teplo

The energy that is transferred from one body or system to another as a result of a difference in temperature. In SI units, heat is measured in joules.

heat capacity

tepelná kapacita

Symbol C. The amount of heat (ΔQ) needed to change the temperature (ΔT) of an object by one degree Kelvin (or Celsius, which is the same size).

C = ΔQ/ΔT.

It is measured in J.K^-1.

heat exchanger

výmenník tepla

A device for transferring heat energy from one fluid to another, without contact between the two fluids.

heat given

teplo odovzdané

heat radiation (radiant heat)

tepelné žiarenie

Energy in the form of electromagnetic waves emitted by a solid, liquid, or gas as a result of its temperature.

heat taken in

teplo prijaté

Heisenberg uncertainty principle

Heisenbergov priníp neurčitosti

The principle that it is not possible to know with unlimited accuracy both the position and momentum of a particle.

It is usually stated in the form

ΔxΔp_x ³ h/4p

where Δx is the uncertainty in the x-coordinate of the particle, Δp_x is the uncertainty in the x-component of the particle’s momentum, and h is the Planck constant.

heliocentric universe

heliocentrický vesmír

A view of the universe in which the sun is taken to be at its centre.

Helmholtz coils

Helmholtzove cievky

A pair of flat parallel coils separated by a distance equal to their radius.

henry

henry

Symbol H. The SI unit of inductance.

Hertzsprung-Russel diagram (H-R diagram)

Hertzsprungov-Russelov diagram

A graphical representation of the absolute magnitude of stars (along y-axis) against the spectral class or colour index (x-axis). The y-axis then represents the energy output of the star and the x-axis its surface temperature. See the H-R diagram.

hidden matter

skrytá hmota

See dark matter.

Higgs boson

Higgsov bozón

A hypothetical particle in the standard model of particle physics. The Higgs boson is responsible for giving mass to all the charged leptons and quarks and is regarded as one of the more unsatisfactory aspects of the standard model. Its mass is about 300 times that of the proton.

high frequency (HF)

vysoká frekvencia

A radio frequency in the range 3 MHz - 30MHz.

high vacuum

vysoké vákuum

A vacuum that has a pressure of 10^-2 - 10^-7 Pa.

hole

diera

A vacant electron position in the lattice structure of a solid that behave like a mobile positive charge carrier with a negative rest energy. See semiconductor.

holography

holografia

A method of recording and displaying a three-dimensional image of an object, usually using coherent radiation from a laser and photographic plates.

Hooke's law

Hookov zákon

The stress (s_n) applied to any solid is proportional to the strain (e) it produces within the elastic limit for that solid.

s_n = Ee,

where E is the Young modulus of elasticity.

horsepower (hp)

konská sila

Imperial unit of power.

1 hp = 745.7 W

Hubble constant

Hubblova konštanta

The rate at which the velocity of recession of the galaxies increases with distance as determined by the redshift.

Hubble Space Telescope

Hubblov vesmírny teleskop

A large astronomical telescope placed in orbit around the Earth in 1990. It operates in the visible, ultraviolet and near-infrared regions of the spectrum.

humidity

vlhkosť

The concentration of water vapour in the atmosphere.

Huygens’ construction

Huygensov princíp

Each point on a wavefront is imagined to be a source of circular waves (called secondary wavelets), and the combined effect of these wavelets gives the position of the next wavefront.

hydrodynamics

hydrodynamika

The study of the motion of incompressible fluids and the interaction of such fluids with their boundaries.

hydrogen spectrum

vodíkové spektrum

The emission spectrum of hydrogen. As an atom of hydrogen has only a single electron its spectrum is fairly simple. It comprises a number of series of spectral lines - the Lyman series in the ultraviolet, the Balmer series in visible light, and the Paschen, Ritz and Brackett-Pfund series in infrared.

hydrostatics

hydrostatika

The study of liquids at rest.

hygrometer

vlhkomer

An instrument for measuring humidity in the atmosphere.

hypermetropia

dalekozrakost

hyperon

hyperón

Any baryon more massive than the neutron. All hyperons have very short half-lives and decay into nucleons.

hypersonic

hyperzvukový

Denoting a velocity in excess of Mach 5.

hysteresis

hysterézia

A phenomenon in which two physical quantities are related in a manner that depends on whether one is increasing or decreasing in relation to the other.

hysteresis loop

hysterézna slučka

The shape of a graph of the hysteresis cycle.

ideal crystal

ideálny kryštál

A single crystal with a perfectly regular lattice that contains no impurities, imperfections, or other defects.

ideal gas

ideálny plyn

A hypothetical gas that obeys the gas laws exactly.

ignition temperature

zápalná teplota

The temperature to which a substance must be heated before it will burn in air.

illuminance

osvetlenie

Symbol E. The energy in the form of visible radiation reaching a surface per unit area in unit time; i.e. the luminous flux per unit area (E = dΦ / dS). It is measured in lux (1 lux = 1 lm.1m^-2)

image

obraz

A representation of a physical object formed by a lens, mirror, or other optical instrument.

immersed

vnorené, ponorené

impedance

impedancia

Symbol Z.

In a d.c. circuit: Z = R, where R is the resistance.

In an a.c. circuit: Z = (R² + X²)^½,

where X is the reactance.

It is measured in ohms.

Imperial units

britské imperiálne jednotky

The British system of units based on the pound (lb) and the yard (yd).

implosion

implózia

An inward collapse of a vessel, especially as a result of evacuation.

impulse

impulz sily

Symbol I. The product of a force F and the time t for which it acts.

impurity

prímes

An atom different from the atoms of a lattice structure that is present in the structure.

in phase

vo fáze

Describing two oscillations that are exactly in step with one another.

inactive electrode

neaktívna elektróda

An electrode used in electrolysis made from a material such as platinum or graphite that does not play any chemical role in the electrolysis.

incident particle

dopadajúca častica, nalietavajúca častica

A particle before it undergoes a change or before it collides with another particle or before it causes a change in the system which is being studied.

incident ray

dopadajúci lúč, prichádzajúci lúč

A ray before it undergoes a change or before it hits a material of different properties, especially before it is refracted, reflected, or absorbed.

incident wave

dopadajúca vlna

A wave before it undergoes a change or before it causes a change in the system which is being studied, especially a wave before it passes an aperture, is refracted, reflected, or absorbed.

inclination

inklinácia, inklinačný uhol

An angle between the orbital plane of a planet, satellite, or comet and the plane of the earth’s ecliptic.

inclined plane

naklonená rovina

One of the six simple machines.

indirectly heated cathode

nepriamo-žeravená katóda

A cathode in a thermionic valve that is heated by placing it close to a heated filament.

induced e.m.f.

indukované elektromotorické napätie

Symbol U_i. The e.m.f. caused by electromagnetic induction.

U_i = -df/dt

inductance

1. indukčnosť

2. induktancia

1. Symbol L or M. The property of an electric circuit or component that causes an e.m.f. to be generated in it as a result of a change in the current flowing through the circuit (self inductance) or of a change in the current flowing through a neighbouring circuit with which it is magnetically linked (mutual inductance).

2. Symbol X_L. A property of an a.c. circuit that together with any capacitance makes up its reactance.

X_L = wL.

It is measured in ohms.

induction

indukcia

A change in the state of a body produced by a field. See electromagnetic induction; inductance.

induction coil

indukčná cievka

A type of transformer used to produce a high-voltage pulses from a low-voltage direct current source. Inductions coils are used to generate the high voltages needed to produce sparks in petrol engine ignition systems.

inductor

induktor, cievka

Any circuit component (e.g. coil) with an inductance.

inelastic collision

nepružná zrážka

A collision in which some of the kinetic energy of the colliding bodies is converted into internal energy in one body so that kinetic energy is not conserved.

inertia

zotrvačnosť

The property of matter that causes it to resist any change in its motion.

inertial frame

inerciálna vztažná sústava

A frame of reference in which bodies move in straight lines with constant speeds unless acted upon by external forces, i.e. a frame of reference in which free bodies are not accelerated.

inertial mass

zotrvačná hmotnosť

Symbol m_i. Mass defined according to Newton’s laws of motion. If two unequal masses, m₁ and m₂, are allowed to collide, in the absence of any other forces both will experience the same force of collision. If the two bodies acquire accelerations a₁ and a₂ as a result of this collision, then

m₁a₁ = m₂a₂.

This equation enables two masses to be compared. If one of the masses is regarded as a standard of mass, the mass of all other masses can be measured in terms of this standard.

Compare gravitational mass.

inertial navigation system (INS)

zotrvačný navigačný systém

A system used to enable aircraft and guided missiles to calculate their position by knowing their starting point and the duration of all accelerations in any direction.

inertial reference frame

inerciálna vztažná sústava

Same as inertial frame.

infinitesimal

nekonečne malý, infinitesimálny

Vanishingly small but not zero.

infrared radiation (IR)

infračervené žiarenie

Electromagnetic radiation with wavelengths longer than that of red light but shorter than radiowaves, i.e. radiation in the wavelength range 0.7 mm to 1 mm.

infrasound

infrazvuk

Soundlike waves with frequencies below the audible limit of about 20 Hz.

input

vstup

insolation

insolácia (prichádzajúce slnečné žiarenie)

The solar radiation that is received at the earth’s surface per unit area. It is measured in MJ.m^-2.

From incoming solar radiation.

instantaneous (adj.)

okamžitý

instantaneous value

okamžitá hodnota

The value of any varying quantity at a specified instant.

insulator

izolátor

A substance that is a poor conductor of heat and electricity.

integrated circuit

integrovaný obvod

A miniature electronic circuit made of a complex array of active devices produced within a single crystal of a semiconductor such as silicon.

intensity

intenzita

Generally, the strength of a field of force. See radiant intensity, electric intensity, magnetic intensity, luminous intensity.

interaction

interakcia, vzájomné pôsobenie

In general, any process in which one object exerts a force on another, or where an object changes its nature in some way. In particle physics, four distinct forms of interaction are known, called the fundamental interactions (or the four forces of nature). These are the strong nuclear interaction, the weak nuclear interaction, the electromagnetic interaction, and the gravitation.

interface

rozhranie (dvoch prostredí)

The boundary between the two media.

interference

interferencia

The interaction of two or more wave motions affecting the same part of a medium so that the instantaneous disturbances in the resultant wave are the vector sum of the instantaneous disturbances in the interfering waves.

interferometer

interferometer

An instrument designed to produce optical interference fringes for measuring wavelengths, testing flat surfaces, measuring small distances, etc.

intermediate frequency

medzifrekvencia

The frequency that is the difference between the transmitted carrier frequency and the locally generated frequency (by the local oscillator of a the receiver). It still retains the transmitted modulation.

intermediate neutron

intermediárny neutrón

A neutron with kinetic energy in the range 10² - 10⁵ eV.

intermediate vector boson

intermediárny vektorový bozón

See W boson; Z boson.

intermolecular forces

medzimolekulové sily

Weak forces occurring between molecules.

internal conversion

vnútorná konverzia

A process in which an excited atomic nucleus decays to the ground state and the energy released is transferred by electromagnetic coupling to one of the bound electrons of that atom rather than being released as a photon.

internal energy

vnútorná energia

Symbol U. The total of the kinetic energies of the atoms and molecules of which a system consists and the potential energies associated with their mutual interactions.

internal resistance

vnútorný odpor

Symbol R_i. The resistance within a source of electric current, such as a cell or generator.

interplanetary space

medziplanetárny priestor

The space between the sun and the planets within the solar system.

interstellar space

medzihviezdny priestor

The space between the stars.

interstitial

intersticiálna poloha častice

Point defect created by an extra atom or ion between two normal lattice points.

intrinsic semiconductor

vlastný polovodič

A semiconductor with no doping and an equal number of electrons and holes.

inverse Compton effect

inverzný Comptonov jav

The gain in energy of low-energy photons when they are scattered by free electrons of much higher energy. As a consequence, the electrons lose energy.

inverter

invertor, hradlo NOT

Same as NOT gate.

ion

ión

An atom or group of atoms that has either lost one or more electrons, making it positively charged (a cation), or gained one or more electrons, making it negatively charged (an anion).

ion pair

iónový pár

ionisation

ionizácia

The process of producing ions.

ionisation potential

ionizačný potenciál

Symbol I. The minimum energy required to remove an electron from a specified atom or molecule to such a distance that there is no electrostatic interaction between ion and electron.

ionising radiation

ionizujúce žiarenie

Radiation of sufficiently high energy to cause ionisation in the medium through which it passes.

ionosphere

ionosféra

The layer of the earth’s atmosphere, 50 - 1000 km above the earth surface.

iris

dúhovka

Part of a human eye.

irradiance

hustota žiarivého toku

Symbol E (also J_e). The radiant flux per unit area reaching a surface.

E = df_e/dS.

It is measured in W.m^-2.

irreversible process

nevratný dej, nevratný proces

Any process that is not reversible, i.e. cannot happen in reverse, usually because to do so would violate the second law of thermodynamics.

isobar

izobara

A curve joining points of equal atmospheric pressure.

isobars

izobary

Nuclides that have the same number of nucleons but different atomic numbers.

isomorphism

izomorfizmus

The existence of two or more substances (isomorphs) that have the same crystal structure, so that they are able to form solid solutions.

isospin

izospin

Short for isotopic spin

isotherm

izoterma

A curve joining points of equal temperature.

isotope

izotop

One of two or more atoms of the same element that have the same number of protons in their nucleus but different numbers of neutrons.

isotopic number

izotopické číslo

The difference between the number of neutrons in an isotope and the number of protons.

isotopic spin (isospin)

izotopický spin

A quantum number applied to hadrons to distinguish between members of a set of particles that differ in their electromagnetic properties but are otherwise apparently identical.

isotropic (adj.)

izotropný

Denoting a material or medium whose physical properties are independent of direction. Compare anisotropic.

isotropic medium

izotropné prostredie

Medium whose physical properties are independent of direction.