Физические законы, переменные, принципы
Municipal Liceum № 57
Laws, rules, principles, effects, paradoxes, limits, constants,
experiments, & thought-experiments in physics.
Pupil : Morozov Michael
Togliatti
1998
Ampere's law (A.M. Ampere)
The line integral of the magnetic flux around a closed curve
isproportional to the algebraic sum of electric currents flowingthrough
that closed curve. This was later modified to add a second term when it
wasincorporated into Maxwell's equations.
Anthropic principle
Weak anthropic principle. The conditions necessary for the
development of intelligent life will be met only in certain regions that
are limited in space and time. That is, the region of the Universe in
which we live is not necessarily representative of a purely random set
of initial conditions; only those favorable to intelligent life would
actually develop creatures who wonder what the initial conditions of
the Universe were.
Strong anthropic principle. A more forceful argument that the weak
principle: It states, rather straightforwardly, that if the laws of the
Universe were not conducive to the development of intelligent creatures to
ask about the initial conditions of the Universe, intelligent life would
never have evolved to ask the question in the first place. In other
words, the laws of the Universe are the way they are because if they
weren't, you would not be able to ask such a question.
Arago spot (D.F.J. Arago)
A bright spot that appears in the shadow of a uniform disc beingbacklit
by monochromatic light emanating from a point source.
Archimedes' principle
A body that is submerged in a fluid is buoyed up by a force equalin
magnitude to the weight of the fluid that is displaced, anddirected upward
along a line through the center of gravity of thedisplaced fluid.
Atwood's machine
A weight-and-pulley system devised to measure the acceleration dueto
gravity at Earth's surface by measuring the net acceleration ofa set of
weights of known mass around a frictionless pulley.
Avogadro constant; L; NA (Count A. Avogadro; 1811)
The number of atoms or molecules in a sample of an idea gas whichis at
standard temperature and pressure. It is equal to about 6.022 52.1023 mol-
1.
Avogadro's hypothesis (Count A. Avogadro; 1811)
Equal volumes of all gases at the same temperature and pressurecontain
equal numbers of molecules. It is, in fact, only true forideal gases.
Balmer series (J. Balmer; 1885)
An equation which describes the emission spectrum of hydrogen whenan
electron is jumping to the second orbital; four of the linesare in the
visible spectrum, and the remainder are in theultraviolet.
Baryon decay
The theory, predicted by several grand-unified theories, that aclass of
subatomic particles called baryons (of which the nucleons-- protons and
neutrons -- are members) are not ultimately stablebut indeed decay.
Present theory and experimentation demonstratethat if protons are indeed
unstable, they decay with a halflife ofat least 1034 y.
Bernoulli's equation
An equation which states that an irrotational fluid flowingthrough a
pipe flows at a rate which is inversely proportional tothe cross-sectional
area of the pipe. That is, if the pipeconstricts, the fluid flows faster;
if it widens, the fluid flowsslower.
BCS theory (J. Bardeen, L.N. Cooper, J.R. Schrieffer; 1957)
A theory put forth to explain both superconductivity andsuperfluidity.
It suggests that in the superconducting (orsuperfluid) state electrons form
Cooper pairs, where two electronsact as a single unit. It takes a nonzero
amount of energy tobreak such pairs, and the imperfections in the
superconductingsolid (which would normally lead to resistance) are
incapable ofbreaking the pairs, so no dissipation occurs and there is
noresistance.
Biot-Savart law (J.B. Biot, F. Savart)
A law which describes the contributions to a magnetic field by
anelectric current. It is analogous to Coulomb's law forelectrostatics.
Blackbody radiation
The radiation -- the radiance at particular frequencies all acrossthe
spectrum -- produced by a blackbody -- that is, a perfectradiator (and
absorber) of heat. Physicists had difficultyexplaining it until Planck
introduced his quantum of action.
Bode's law
A mathematical formula which generates, with a fair amount ofaccuracy,
the semimajor axes of the planets in order out from theSun. Write down the
sequence 0, 3, 6, 12, 24, . . . and then add4 to each term. Then divide
each term by 10. This is intended togive you the positions of the planets
measured in astronomicalunits.
Bode's law had no theoretical justification when it was
firstintroduced; it did, however, agree with the soon-to-be-
discoveredplanet Uranus' orbit (19.2 au actual; 19.7 au
predicted).Similarly, it predicted a missing planet betwen Mars and
Jupiter,and shortly thereafter the asteroids were found in very
similarorbits (2.8 au actual for Ceres; 2.8 au predicted). However,
theseries seems to skip over Neptune's orbit.
Bohr magneton (N. Bohr)
The quantum of magnetic moment.
Bohr radius (N. Bohr)
The distance corresponding the mean distance of an electron fromthe
nucleus in the ground state.
Boltzmann constant; k (L. Boltzmann)
A constant which describes the relationship between temperatureand
kinetic energy for molecules in an ideal gas. It is equal to1.
Boyle's law (R. Boyle; 1662); Mariotte's law (E. Mariotte; 1676)
The product of the pressure and the volume of an ideal gas atconstant
temperature is a constant.
Brackett series (Brackett)
The series which describes the emission spectrum of hydrogen whenthe
electron is jumping to the fourth orbital. All of the linesare in the
infrared portion of the spectrum.
Bragg's law (Sir W.L. Bragg; 1912)
When a beam of x-rays strikes a crystal surface in which thelayers of
atoms or ions are regularly separated, the maximumintensity of the
reflected ray occurs when the sine of thecompliment of the angle of
incidence is equal to an integermultiplied by the wavelength of x-rays
divided by twice thedistance between layers of atoms or ions.
Brewster's law (D. Brewster)
The extent of the polarization of light reflected from atransparent
surface is a maximum when the reflected ray is atright angles to the
refracted ray.
Brownian motion (R. Brown; 1827)
The continuous random motion of solid microscopic particles
whensuspended in a fluid medium due to the consequence of
continuousbombardment by atoms and molecules.
Carnot's theorem (S. Carnot)
The theorem which states that no engine operating between
twotemperatures can be more efficient than a reversible engine.
centrifugal pseudoforce
A pseudoforce -- a fictitious force resulting from being in a non-
inertial frame of reference -- that occurs when one is moving inuniform
circular motion. One feels a "force" outward from thecenter of motion.
Chandrasekhar limit (S. Chandrasekhar; 1930)
A limit which mandates that no white dwarf (a collapsed,degenerate
star) can be more massive than about 1.2 solar masses.Anything more massive
must inevitably collapse into a neutronstar.
Charles' law (J.A.C. Charles; c. 1787)
The volume of an ideal gas at constant pressure is proportional tothe
thermodynamic temperature of that gas.
Cherenkov radiation (P.A. Cherenkov)
Radiation emitted by a massive particle which is moving fasterthan
light in the medium through which it is travelling. Noparticle can travel
faster than light in vacuum, but the speed oflight in other media, such as
water, glass, etc., are considerablylower. Cherenkov radiation is the
electromagnetic analogue of thesonic boom, though Cherenkov radiation is a
shockwave set up inthe electromagnetic field.
Complementarity principle (N. Bohr)
The principle that a given system cannot exhibit both wave-likebehavior
and particle-like behavior at the same time. That is,certain experiments
will reveal the wave-like nature of a system,and certain experiments will
reveal the particle-like nature of asystem, but no experiment will reveal
both simultaneously.
Compton effect (A.H. Compton; 1923)
An effect that demonstrates that photons (the quantum ofelectromagnetic
radiation) have momentum. A photon fired at astationary particle, such as
an electron, will impart momentum tothe electron and, since its energy has
been decreased, willexperience a corresponding decrease in frequency.
Coriolis pseudoforce (G. de Coriolis; 1835)
A pseudoforce -- a fictitious force, like the centrifugal "force"--
which arises because the rotation of the Earth varies atdifferent
latitutdes (maximum at the equator, zero at the poles).
correspondence principle.
The principle that when a new, more specialized theory is putforth, it
must reduce to the more general (and usually simpler)theory under normal
circumstances. There are correspondenceprinciples for general relativity
to special relativity andspecial relativity to Newtonian mechanics, but the
most widelyknown correspondence principle (and generally what is meant
whenone says "correspondence principle") is that of quantum mechanicsto
classical mechanics.
Cosmic background radiation; primal glow
The background of radiation mostly in the frequency range 3.1011 to
3.108 Hz discovered in space in 1965. It is believedto be the
cosmologically redshifted radiation released by the BigBang itself.
Presently it has an energy density in empty space ofabout
Cosmological redshift
An effect where light emitted from a distant source appearsredshifted
because of the expansion of space itself. Compare withthe Doppler effect.
Coulomb's law
The primary law for electrostatics, analogous to Newton's law
ofuniversal gravitation. It states that the force between two pointcharges
is proportional to the algebraic product of theirrespective charges as well
as proportional to the inverse squareof the distance between them.
