*A constant which describes the relationship between
temperatureand kinetic energy for molecules in an ideal gas. It is
equal to1.*
*The background of radiation mostly in the frequency
range 3*^{.}*10*^{11}*
to 3*^{.}*10*^{8}* 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 *
*The constant which determines the relationship between
thedistance to a galaxy and its velocity of recession due to
theexpansion of the Universe. It is not known to great accuracy,
butis believed to lie between 49 and 95*
**deal gas constant; universal molar gas constant; R**

Полнотекстовый поиск по базе:

*Municipal
Liceum **№
**57*

*L**aws**,
rules, principles, effects, paradoxes, limits, constant**s**,
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.*

**A****nthropic
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; N**_{A}** (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*^{.}*10*^{23}*
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.*

**B****aryon
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 10*^{34}*
**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.*

**B****lackbody
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)**

*380 622 *^{.}*
10*^{-23}__ J__

*K.*

**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.*

**C****omplementarity
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.*

**C****osmic
background radiation; primal glow**

*4*^{.}*10*^{-14}__
J__

*m*^{3}*.*

**C****osmological
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.*

**CPT
theorem**

**Curie-Weiss
law (P. Curie, P.-E. Weiss)**

*A
more general form of Curie's law, which states that thesusceptibility
of a paramagnetic substance is inverselyproportional to the
thermodynamic temperature of the substanceless the Weiss constant, a
characteristic of that substance.*

**Curie's
law (P. Curie)**

*The
susceptibility of a paramagnetic substance is inverselyproportional
to the thermodynamic temperature of the substance.The constant of
proportionality is called the Curie constant.*

**Dalton's
law of partial pressures (J. Dalton)**

*The
total pressure of a mixture of ideal gases is equal to the sumof the
partial pressures of its components; that is, the sum ofthe pressures
that each component would exert if it were presentalone and occuped
the same volume as the mixture.*

**Davisson-Germer
experiment (C.J. Davisson, L.H. Germer; 1927)**

*An
experiment that conclusively confirmed the wave nature ofelectrons;
diffraction patterns were observed by an electron beampenetrating
into a nickel target.*

**D****e
Broglie wavelength (L. de Broglie; 1924)**

*The
prediction that particles also have wave characteristics,where the
effective wavelength of a particle would be inverselyproportional to
its momentum, where the constant ofproportionality is the Planck
constant.*

**Doppler
effect (C.J. Doppler)**

*Waves
emitted by a moving observer will be blueshifted(compressed) if
approaching, redshifted (elongated) if receding.It occurs both in
sound as well as electromagnetic phenomena,although it takes on
different forms in each.*

**Dulong-Petit
law (P. Dulong, A.T. Petit; 1819)**

*The
molar heat capacity is approximately equal to the three timesthe gas
constant.*

**Einstein-Podolsky-Rosen
effect**

*Consider the following quantum mechanical thought-experiment:Take
a particle which is at rest and has spin zero. Itspontaneously
decays into two fermions (spin **0.5**
particles), whichstream away in opposite directions at high speed.
Due to the lawof conservation of spin, we know that one is a spin
+**0.5 ** and theother is spin
-**0.5**. Which one is which?
According to quantummechanics, neither takes on a definite state
until it is observed(the wavefunction is collapsed).*

*The
EPR effect demonstrates that if one of the particles isdetected, and
its spin is then measured, then the other particle-- no matter where
it is in the Universe -- instantaneously isforced to choose as well
and take on the role of the otherparticle. This illustrates that
certain kinds of quantuminformation travel instantaneously; not
everything is limited bythe speed of light.*

*However, it can be easily demonstrated that this effect doesnot
make faster-than-light communication possible.*

**E****quivalence
principle**

*The
basic postulate of A. Einstein's general theory of relativity,which
posits that an acceleration is fundamentallyindistinguishable from a
gravitational field. In other words, ifyou are in an elevator which
is utterly sealed and protected fromthe outside, so that you cannot
"peek outside," then if you feel aforce (weight), it is
fundamentally impossible for you to saywhether the elevator is
present in a gravitational field, orwhether the elevator has rockets
attached to it and isaccelerating "upward."*

*The
equivalence principle predicts interesting generalrelativistic
effects because not only are the twoindistinguishable to human
observers, but also to the Universe aswell, in a way -- any effect
that takes place when an observer isaccelerating should also take
place in a gravitational field, andvice versa.*

**E****rgosphere**

*The
region around a rotating black hole, between the event horizonand the
static limit, where rotational energy can be extractedfrom the black
hole.*

**E****vent
horizon**

*The
radius of surrounding a black hole at which a particle wouldneed an
escape velocity of lightspeed to escape; that is, thepoint of no
return for a black hole.*

**Faraday
constant; F (M. Faraday)**

*The
electric charge carried by one mole of electrons (or singly-ionized
ions). It is equal to the product of the Avogadroconstant and the
(absolute value of the) charge on an electron; itis *

*9.648670*^{.}*10*^{4}*
C/mol.*

**Faraday's
law (M. Faraday)**

*The
line integral of the electric flux around a closed curve
isproportional to the instantaneous time rate of change of
themagnetic flux through a surface bounded by that closed curve.*

**Faraday's
laws of electrolysis (M. Faraday)**

*The amount of chemical change during electrolysis is proportional to the charge passed.*

*2. The charge required to deposit or liberate a mass is
proportional to the charge of the ion, the mass, and inversely
proprtional to the relative ionic mass. The constant of
proportionality is the Faraday constant.*

**Faraday's
laws of electromagnetic induction (M. Faraday)**

*An electromotive force is induced in a conductor when the magnetic field surrounding it changes.*

*The magnitude of the electromotive force is proportional to the rate of change of the field.*

*3. The sense of the induced electromotive force depends on the
direction of the rate of the change of the field.*

**Fermat's
principle; principle of least time (P. de Fermat)**

*The
principle, put forth by P. de Fermat, states that the pathtaken by a
ray of light between any two points in a system isalways the path
that takes the least time.*

**Fermi
paradox**

*E.
Fermi's conjecture, simplified with the phrase, "Where arethey?"
questioning that if the Galaxy is filled with intelligentand
technological civilizations, why haven't they come to us yet?There
are several possible answers to this question, but since weonly have
the vaguest idea what the right conditions for life andintelligence
in our Galaxy, it and Fermi's paradox are no morethan speculation.*

**Gauss'
law (K.F. Gauss)**

*The
electric flux through a closed surface is proportional to
thealgebraic sum of electric charges contained within that
closedsurface.*

**Gauss'
law for magnetic fields (K.F. Gauss)**

*The
magnetic flux through a closed surface is zero; no magneticcharges
exist.*

**G****randfather
paradox**

*A
paradox proposed to discount time travel and show why itviolates
causality. Say that your grandfather builds a timemachine. In the
present, you use his time machine to go back intime a few decades to
a point before he married his wife (yourgrandmother). You meet him
to talk about things, and an argumentensues (presumably he doesn't
believe that you're hisgrandson/granddaughter), and you accidentally
kill him.*

*If
he died before he met your grandmother and never hadchildren, then
your parents could certainly never have met (one ofthem didn't
exist!) and could never have given birth to you. Inaddition, if he
didn't live to build his time machine, what areyou doing here in the
past alive and with a time machine, if youwere never born and it was
never built?*

**Hall
effect**

*When
charged particles flow through a tube which has both anelectric field
and a magnetic field (perpendicular to the electricfield) present in
it, only certain velocities of the chargedparticles are preferred,
and will make it undeviated through thetube; the rest will be
deflected into the sides. This effect isexploited in such devices as
the mass spectrometer and in theThompson experiment. This is called
the Hall effect.*

**Hawking
radiation (S.W. Hawking; 1973)**

*The
theory that black holes emit radiation like any other hotbody.
Virtual particle-antiparticle pairs are constantly beingcreated in
supposedly empty space. Every once in a while, onewill be created in
the vicinity of a black hole's event horizon.One of these particles
might be catpured by the black hole,forever trapped, while the other
might escape the black hole'sgravity. The trapped particle, which
would have negative energy(by definition), would reduce the mass of
the black hole, and theparticle which escaped would have positive
energy. Thus, from adistant, one would see the black hole's mass
decrease and aparticle escape the vicinity; it would appear as if the
black holewere emitting radiation. The rate of emission has a
negativerelationship with the mass of the black hole; massive black
holesemit radiation relatively slowly, while smaller black holes
emitradiation -- and thus decrease their mass -- more rapidly.*

**Heisenberg
uncertainty principle (W. Heisenberg; 1927)**

*A
principle, central to quantum mechanics, which states that
themomentum (mass times velocity) and the position of a
particlecannot both be known to infinite accuracy; the more you know
aboutone, the lest you know about the other.*

*It
can be illustrated in a fairly clear way as follows: Tosee something
(let's say an electron), we have to fire photons atit, so they bounce
off and come back to us, so we can "see" it.If you choose
low-frequency photons, with a low energy, they donot impart much
momentum to the electron, but they give you a veryfuzzy picture, so
you have a higher uncertainty in position sothat you can have a
higher certainty in momentum. On the otherhand, if you were to fire
very high-energy photons (x-rays orgammas) at the electron, they
would give you a very clear pictureof where the electron is (high
certainty in position), but wouldimpart a great deal of momentum to
the electron (higheruncertainty in momentum). In a more
generalized sense, the uncertainty principle tellsus that the act of
observing changes the observed in fundamentalway.*

**Hooke's
law (R. Hooke)**

*The
stress applied to any solid is proportional to the strain itproduces
within the elastic limit for that solid. The constant ofthat
proportionality is the Young modulus of elasticity for thatsubstance.*

**Hubble
constant; H**_{0}** (E.P. Hubble;
1925)**

__ ____Km____
.__

*s*^{.}*Mpc*

**Hubble's
law (E.P. Hubble; 1925)**

*A
relationship discovered between distance and radial velocity.The
further away a galaxy is away from is, the faster it isreceding away
from us. The constant of proportionality isHubble's constant, H*_{0}*.
The cause is interpreted as the expansionof space itself.*

**Huygens'
construction; Huygens' principle (C. Huygens)**

*The
mechanics propagation of a wave of light is equivalent toassuming
that every point on the wavefront acts as point source ofwave
emission.*

**I**

__ ____J____
.__

*K*^{.}*mol*

*The
constant that appears in the ideal gas equation. It is equalto 8.314
34.*

**Ideal
gas equation**

*An
equation which sums up the ideal gas laws in one simpleequation. It
states that the product of the pressure and thevolume of a sample of
ideal gas is equal to the product of theamount of gas present, the
temperature of the sample, and theideal gas constant.*

**I****deal
gas laws**

**Boyle's law.*** The pressure of an ideal gas is
inversely proportional to the volume of the gas at constant
temperature.*

**Charles' law.*** The volume of an ideal gas is
directly proportional to the thermodynamic temperature at constant
pressure.*

**The
pressure law.*** The pressure of an ideal gas is directly**
**proportional to the thermodynamic temperature at
constant volume.*

**Joule-Thomson
effect; Joule-Kelvin effect (J. Joule, W. Thomson)**

*The
change in temperature that occurs when a gas expands into aregion of
lower pressure.*

**Joule's
laws**

**Joule's first law. ***The heat produced when an
electric current flows through a resistance for a specified time is
equal to** **the square of the
current multiplied by the resistivity**
**multiplied by the time.*

**Joule's second law. ***The internal energy of an ideal
gas is independent of its volume and pressure, depending only on its
temperature.*

**Josephson
effects (B.D. Josephson; 1962)**

*Electrical effects observed when two superconducting materials
areseparated by a thin layer of insulating material.*

**Kepler's
laws (J. Kepler)**

**Kepler's first law***. A planet orbits the Sun in an
ellipse with the Sun at one focus.*

**Kepler's second law***. A ray directed from the Sun to
a planet sweeps out equal areas in equal times.*

**Kepler's third law***. The square of the period of a
planet's orbit is proportional to the cube of that planet's semimajor
axis; the constant of proportionality is the same for all planets.*

**Kerr
effect (J. Kerr; 1875)**

*The
ability of certain substances to differently refract lightwaves whose
vibrations are in different directions when thesubstance is placed in
an electric field.*

**Kirchhoff's
law of radiation (G.R. Kirchhoff)**

*The
emissivity of a body is equal to its absorptance at the
sametemperature.*

**Kirchhoff's
rules (G.R. Kirchhoff)**

**The
loop rule.*** The sum of the potential differences
encountered in a round trip around any closed loop in a circuit is
zero.*

**The
point rule.*** The sum of the currents toward a branch point
is equal to the sum of the currents away from the same branch**
**point.*

**Kohlrausch's
law (F. Kohlrausch)**

*If
a salt is dissolved in water, the conductivity of the solutionis the
sum of two values -- one depending on the positive ions andthe other
on the negative ions.*

**Lambert's
laws (J.H. Lambert)**

**Lambert's first law.*** The illuminance on a surface
illuminated by** **light falling
on it perpendicularly from a point source is**
**proportional to the inverse square of the distance
between the** **surface and the
source.*

**Lambert's second law.*** If the rays meet the surface
at an angle, then the illuminance is also proportional to the cosine
of the angle with the normal.*

**Lambert's third law.*** The luminous intensity of
light decreases exponentially with the distance that it travels
through an absorbing medium.*

**Landauer's
principle**

*A
principle which states that it doesn't explicitly take energy
tocompute data, but rather it takes energy to erase**
**any data,since erasure is an important step in
computation.*

**Laplace's
equation (P. Laplace)**

*For
steady-state heat conduction in one dimension, the
temperaturedistribution is the solution to Laplace's equation, which
statesthat the second derivative of temperature with respect
todisplacement is zero.*

**Laue
pattern (M. von Laue)**

*The
pattern produced on a photographic film when
high-frequencyelectromagnetic waves (such as x-rays) are fired at a
crystallinesolid.*

**L****aws
of conservation**

*A
law which states that, in a closed system, the total quantity
ofsomething will not increase or decrease, but remain exactly
thesame. For physical quantities, it states that something
canneither be created nor destroyed.*

*The
most commonly seen are the laws of conservation of mass-energy
(formerly two conservation laws before A. Einstein), ofelectric
charge, of linear momentum, and of angular momentum.There are several
others that deal more with particle physics,such as conservation of
baryon number, of strangeness, etc., whichare conserved in some
fundamental interactions but not others.*

**L****aw
of reflection**

*For
a wavefront intersecting a reflecting surface, the angle ofincidence
is equal to the angle of reflection.*

**L****aws
of black hole dynamics**

**First
law of black hole dynamics.*** For interactions between
black holes and normal matter, the conservation laws of total energy,
total momentum, angular momentum, and electric charge, hold.*

**Second law of black hole dynamics.*** With black hole
interactions, or interactions between black holes and normal matter,
the sum** **of the surface areas
of all black holes involved can never**
**decrease.*

**L****aws
of thermodynamics**

**First
law of thermodynamics.*** The change in internal energy of a
system is the sum of the heat transferred to or from the system and
the work done on or by the system.*

**Second law of thermodynamics.*** The entropy -- a
measure of the unavailability of a system's energy to do useful work
-- of a** **closed system tends
to increase with time.*

**Third
law of thermodynamics.*** For changes involving only perfect
crystalline solids at absolute zero, the change of the total entropy
is zero.*

**Zeroth law of thermodynamics.*** If two bodies are
each in thermal equilibrium with a third body, then all three bodies
are in thermal equilibrium with each other.*

**Lawson
criterion (J.D. Lawson)**

*A
condition for the release of energy from a thermonuclearreactor. It
is usually stated as the minimum value for theproduct of the density
of the fuel particles and the containmenttime for energy breakeven.
For a half-and-half mixture ofdeuterium and tritium at ignition
temperature, n*_{G}* **
is between10*^{14}* and 10*^{15}*
s/cm*^{3}*.*

**Le
Chatelier's principle (H. Le Chatelier; 1888)**

*If
a system is in equilibrium, then any change imposed on thesystem
tends to shift the equilibrium to reduce the effect of thatapplied
change.*

**Lenz's
law (H.F. Lenz; 1835)**

*An
induced electric current always flows in such a direction thatit
opposes the change producing it.*

**Loschmidt
constant; Loschmidt number; N**_{L}

*The
number of particles per unit volume of an ideal gas atstandard
temperature and pressure. It has the value 2.68719*^{.}*10*^{25}*
m*^{-3.}

**L****umeniferous
aether**

*A
substance, which filled all the empty spaces between matter,which was
used to explain what medium light was "waving" in. Nowit
has been discredited, as Maxwell's equations imply
thatelectromagnetic radiation can propagate in a vacuum, since
theyare disturbances in the electromagnetic field rather
thantraditional waves in some substance, such as water waves.*

**Lyman
series**

*The
series which describes the emission spectrum of hydrogen
whenelectrons are jumping to the ground state. All of the lines
arein the ultraviolet.*

**Mach's
principle (E. Mach; 1870s)**

*The
inertia of any particular particle or particles of matter
isattributable to the interaction between that piece of matter andthe
rest of the Universe. Thus, a body in isolation would have
noinertia.*

**Magnus
effect**

*A
rotating cylinder in a moving fluid drags some of the fluidaround
with it, in its direction of rotation. This increases thespeed in
that region, and thus the pressure is lower.Consequently, there is a
net force on the cylinder in thatdirection, perpendicular to the flow
of the fluid. This is calledthe Magnus effect.*

**Malus's
law (E.L. Malus)**

*The
light intensity travelling through a polarizer is proportionalto the
initial intensity of the light and the square of the cosineof the
angle between the polarization of the light ray and thepolarization
axis of the polarizer.*

**Maxwell's
demon (J.C. Maxwell)**

*A
thought experiment illustrating the concepts of entropy. Wehave a
container of gas which is partitioned into two equal sides;each side
is in thermal equilibrium with the other. The walls(and the
partition) of the container are a perfect insulator. Now imagine
there is a very small demon who is waiting at thepartition next to a
small trap door. He can open and close thedoor with negligible work.
Let's say he opens the door to allow afast-moving molecule to travel
from the left side to the right, orfor a slow-moving molecule to
travel from the right side to the** **left,
and keeps it closed for all other molecules. The net effectwould be
a flow of heat -- from the left side to the right -- eventhough the
container was in thermal equilibrium. This is clearlya violation of
the second law of thermodynamics. So where did we go wrong? It
turns out that information hasto do with entropy as well. In order
to sort out the moleculesaccording to speeds, the demon would be
having to keep a memory ofthem -- and it turns out that increase in
entropy of the simplemaintenance of this simple memory would more
than make up for thedecrease in entropy due to the heat flow.*

**Maxwell's
equations (J.C. Maxwell; 1864)**

*Four
elegant equations which describe classical electromagnetismin all its
splendor. They are: *

**Gauss' law.*** The electric flux through a closed
surface is proportional to the algebraic sum of electric charges
contained within that closed surface.*

**Gauss' law for magnetic fields.*** The magnetic flux
through a closed surface is zero; no magnetic charges exist.*

**Faraday's law.*** The line integral of the electric
flux around a closed curve is proportional to the instantaneous time
rate of change of the magnetic flux through a surface bounded by that
closed curve.*

**Ampere's law, modified form.*** The line integral of
the magnetic flux around a closed curve is proportional to the sum of
two terms: first, the algebraic sum of electric currents flowing
through that closed curve; and second, the instantaneous time rate of
change of the electric flux through a surface bounded by that closed
curve.*

*In
addition to describing electromagnetism, his equations alsopredict
that waves can propagate through the electromagneticfield, and would
always propagate at the same speed -- these are**
**electromagnetic waves.*

**Meissner
effect (W. Meissner; 1933)**

*The
decrease of the magnetic flux within a superconducting metalwhen it
is cooled below the critical temperature. That is,superconducting
materials reflect magnetic fields.*

**Michelson-Morley
experiment (A.A. Michelson, E.W. Morley; 1887)**

*Possibly the most famous null-experiment of all time, designed
toverify the existence of the proposed "lumeniferous aether"
throughwhich light waves were thought to propagate. Since the
Earthmoves through this aether, a lightbeam fired in the
Earth'sdirection of motion would lag behind one fired sideways, where
noaether effect would be present. This difference could be
detectedwith the use of an interferometer.*

*The
experiment showed absolutely no aether shift whatsoever,where one
should have been quite detectable. Thus the aetherconcept was
discredited as was the constancy of the speed oflight.*

**Millikan
oil drop experiment (R.A. Millikan)**

*A
famous experiment designed to measure the electronic charge.Drops of
oil were carried past a uniform electric field betweencharged plates.
After charging the drop with x-rays, he adjustedthe electric field
between the plates so that the oil drop wasexactly balanced against
the force of gravity. Then the charge onthe drop would be known.
Millikan did this repeatedly and foundthat all the charges he
measured came in integer multiples only ofa certain smallest value,
which is the charge on the electron.*

**Newton's
law of universal gravitation (Sir I. Newton)**

*Two
bodies attract each other with equal and opposite forces;
themagnitude of this force is proportional to the product of the
twomasses and is also proportional to the inverse square of
thedistance between the centers of mass of the two bodies.*

**Newton's
laws of motion (Sir I. Newton)**

**Newton's first law of motion.*** A body continues in
its state of rest or of uniform motion unless it is acted upon by an
external force.*

**Newton's second law of motion.*** For an unbalanced
force acting on a body, the acceleration produces is proportional to
the force impressed; the constant of proportionality is the inertial
mass of the body.*

**Newton's third law of motion.*** In a system where no
external forces are present, every action is always opposed by an
equal** **and opposite reaction.*

**Ohm's
law (G. Ohm; 1827)**

*The
ratio of the potential difference between the ends of aconductor to
the current flowing through it is constant; theconstant of
proportionality is called the resistance, and isdifferent for
different materials.*

**Olbers'
paradox (H. Olbers; 1826)**

*If
the Universe is infinite, uniform, and unchanging then theentire sky
at night would be bright -- about as bright as the Sun.The further
you looked out into space, the more stars there wouldbe, and thus in
any direction in which you looked your line-of-sight would eventually
impinge upon a star. The paradox isresolved by the Big Bang theory,
which puts forth that theUniverse is not infinite, non-uniform, and
changing.*

**Pascal's
principle**

*Pressure applied to an enclosed imcompressible static fluid
istransmitted undiminished to all parts of the fluid.*

**Paschen
series**

*The
series which describes the emission spectrum of hydrogen whenthe
electron is jumping to the third orbital. All of the linesare in the
infrared portion of the spectrum.*

**Pauli
exclusion principle (W. Pauli; 1925)**

*No
two identical fermions in a system, such as electrons in anatom, can
have an identical set of quantum numbers.*

**Peltier
effect (J.C.A. Peltier; 1834)**

*The
change in temperature produced at a junction between twodissimilar
metals or semiconductors when an electric currentpasses through the
junction.*

**permeability
of free space***; magnetic constant; *_{
0}

*The
ratio of the magnetic flux density in a substance to theexternal
field strength for vacuum. It is equal to 4**
*^{.}* 10*^{-7}*
**H/m.*

**permittivity
of free space;*** electric constant; *_{0}

*The
ratio of the electric displacement to the intensity of theelectric
field producing it in vacuum. It is equal to 8.854*^{.}*10*^{-12}*
F/m.*

**Pfund
series**

*The
series which describes the emission spectrum of hydrogen whenthe
electron is jumping to the fifth orbital. All of the linesare in the
infrared portion of the spectrum.*

**P****hotoelectric
effect**

*An
effect explained by A. Einstein that demonstrate that lightseems to
be made up of particles, or photons. Light can exciteelectrons
(called photoelectrons) to be ejected from a metal.Light with a
frequency below a certain threshold, at anyintensity, will not cause
any photoelectrons to be emitted fromthe metal. Above that
frequency, photoelectrons are emitted inproportion to the intensity
of incident light. The reason is that a photon has energy in
proportion to itswavelength, and the constant of proportionality is
Planck'sconstant. Below a certain frequency -- and thus below a
certainenergy -- the incident photons do not have enough energy to
knockthe photoelectrons out of the metal. Above that threshold
energy,called the workfunction, photons will knock the photoelectrons
outof the metal, in proportion to the number of photons (theintensity
of the light). At higher frequencies and energies, thephotoelectrons
ejected obtain a kinetic energy corresponding tothe difference
between the photon's energy and the workfunction.*

**Planck
constant; h**

*The
fundamental constant equal to the ratio of the energy of aquantum of
energy to its frequency. It is the quantum of action.It has the
value 6.626196*^{.}*10*^{-34}*
J*^{.}*s.*

**Planck's
radiation law**

*A
law which more accurately described blackbody radiation becauseit
assumed that electromagnetic radiation is quantized.*

**Poisson
spot (S.D. Poisson)**

*See
Arago spot. Poisson predicted the existence of such a spot,and
actually used it to demonstrate that the wave theory of lightmust be
in error.*

**P****rinciple
of causality**

*The
principle that cause must always preceed effect. Moreformally, if an
event A ("the cause") somehow influences an eventB ("the
effect") which occurs later in time, then event B cannotin turn
have an influence on event A. The principle is best illustrated
with an example. Say thatevent A constitutes a murderer making the
decision to kill hisvictim, and that event B is the murderer actually
committing theact. The principle of causality puts forth that the
act ofmurder cannot have an influence on the murderer's decision
tocommit it. If the murderer were to somehow see himself
committingthe act and change his mind, then a murder would have
beencommitted in the future without a prior cause (he changed
hismind). This represents a causality violation. Both time
traveland faster-than-light travel both imply violations of
causality,which is why most physicists think they are impossible, or
atleast impossible in the general sense.*

**P****rinciple
of determinism**

*The
principle that if one knows the state to an infinite accuracyof a
system at one point in time, one would be able to predict thestate of
that system with infinite accuracy at any other time,past or future.
For example, if one were to know all of thepositions and velocities
of all the particles in a closed system,then determinism would imply
that one could then predict thepositions and velocities of those
particles at any other time.This principle has been disfavored due to
the advent of quantummechanics, where probabilities take an important
part in theactions of the subatomic world, and the Heisenberg
uncertaintyprinciple implies that one cannot know both the position
andvelocity of a particle to arbitrary precision.*

**Rayleigh
criterion; resolving power**

*A
criterion for the how finely a set of optics may be able
todistinguish. It begins with the assumption that central ring ofone
image should fall on the first dark ring of the other.relativity
principle; principle of relativity*

**Rydberg
formula**

*A
formula which describes all of the characteristics of
hydrogen'sspectrum, including the Balmer, Lyman, Paschen, Brackett,
andPfund series.*

**Schroedinger's
cat (E. Schroedinger; 1935)**

*A
thought experiment designed to illustrate the counterintuitiveand
strange notions of reality that come along with quantummechanics.*

*A
cat is sealed inside a closed box; the cat has ample air,food, and
water to survive an extended period. This box isdesigned so that no
information (i.e., sight, sound, etc.) canpass into or out of the box
-- the cat is totally cut off fromyour observations. Also inside the
box with the poor kitty(apparently Schroedinger was not too fond of
felines) is a phialof a gaseous poison, and an automatic hammer to
break it, floodingthe box and killing the cat. The hammer is hooked
up to a Geigercounter; this counter is monitoring a radioactive
sample and isdesigned to trigger the hammer -- killing the cat --
should aradioactive decay be detected. The sample is chosen so
thatafter, say, one hour, there stands a fifty-fifty chance of a
decayoccurring.*

*The
question is, what is the state of the cat after that onehour has
elapsed? The intuitive answer is that the cat is eitheralive or
dead, but you don't know which until you look. But it**
**is one of them. Quantum mechanics, on the other hands,
saysthat the wavefunction describing the cat is in a superposition
ofstates: the cat is, in fact, fifty per cent alive and fifty
percent dead; it is both. Not until one looks and "collapses
thewavefunction" is the Universe forced to choose either a live
cator a dead cat and not something in between.*

*This
indicates that observation also seems to be an importantpart of the
scientific process -- quite a departure from theabsolutely objective,
deterministic way things used to be withNewton.*

**Schwarzchild
radius**

*The
radius that a spherical mass must be compressed to in order
totransform it into a black hole; that is, the radius of
compressionwhere the escape velocity at the surface would reach
lightspeed.*

**Snell's
law; law of refraction**

*A
relation which relates the change in incidence angle of awavefront
due to refraction between two different media.*

**S****peed
of light in vacuo**

*One
of the postulates of A. Einstein's special theory ofrelativity, which
puts forth that the speed of light in vacuum --often written c, and
which has the value 299 792 458 m/s -- ismeasured as the same speed
to all observers, regardless of theirrelative motion. That is, if
I'm travelling at 0.9 c away fromyou, and fire a beam of light in
that direction, both you and Iwill independently measure the speed of
that beam as c. One of the results of this postulate (one of the
predictionsof special relativity is that no massive particle can
beaccelerated to (or beyond) lightspeed, and thus the speed of
lightalso represents the ultimate cosmic speed limit. Only
masslessparticles (photons, gravitons, and possibly neutrinos, should
theyindeed prove to be massless) travel at lightspeed, and all
otherparticles must travel at slower speeds.*

**Sp****in-orbit
effect**

*An
effect that causes atomic energy levels to be split becauseelectrons
have intrinsic angular momentum (spin) in addition totheir extrinsic
orbital angular momentum.*

**S****tatic
limit**

*The
distance from a rotating black hole where no observer canpossibly
remain at rest (with respect to the distant stars)because of inertial
frame dragging.*

**Stefan-Boltzmann
constant; sigma (Stefan, L. Boltzmann)**

*The
constant of proportionality present in the Stefan-Boltzmannlaw. It
is equal to*

*5.6697*^{.}*10*^{-8}__
W__

*m*^{2}^{.}*K*^{4}*.*

**Stefan-Boltzmann
law (Stefan, L. Boltzmann)**

*The
radiated power (rate of emission of electromagnetic energy) ofa hot
body is proportional to the emissivity, an efficiencyrating, the
radiating surface area, and the fourth power of thethermodynamic
temperature. The constant of proportionality is theStefan-Boltzmann
constant.*

**Stern-Gerlach
experiment (O. Stern, W. Gerlach; 1922)**

*An
experiment that demonstrates the features of spin (intrinsicangular
momentum) as a distinct entity apart from orbital angularmomentum.*

**S****uperconductivity**

*The
phenomena by which, at sufficiently low temperatures, aconductor can
conduct charge with zero resistance.*

**Superfluidity**

*The
phenomena by which, at sufficiently low temperatures, a fluidcan flow
with zero viscosity.*

**Superposition
principle of forces**

*The
net force on a body is equal to the sum of the forcesimpressed upon
it.*

**Superposition
principle of states**

*The
resultant quantum mechnical wavefunction due to two or moreindividual
wavefunctions is the sum of the individualwavefunctions.*

**Superposition
principle of waves**

*The
resultant wave function due to two or more individual wavefunctions
is the sum of the individual wave functions.*

**Thomson
experiment; Kelvin effect (Sir W. Thomson [later Lord Kelvin])**

*When
an electric current flows through a conductor whose ends
aremaintained at different temperatures, heat is released at a
rateapproximately proportional to the product of the current and
thetemperature gradient.*

**T****win
paradox**

*One
of the most famous "paradoxes" in history, predicted by
A.Einstein's special theory of relativity. Take two twins, born
onthe same date on Earth. One, Albert, leaves home for a triparound
the Universe at very high speeds (very close to that oflight), while
the other, Henrik, stays at home at rests. Specialrelativity
predicts that when Albert returns, he will find himselfmuch younger
than Henrik. That is actually not the paradox. The paradox stems
fromattempting to naively analyze the situation to figure out
why.From Henrik's point of view (and from everyone else on
Earth),Albert seems to speed off for a long time, linger around, and
thenreturn. Thus he should be the younger one, which is what we
see.But from Albert's point of view, it's Henrik (and the whole of
the** **Earth) that are
travelling, not he. According to specialrelativity, if Henrik is
moving relative to Albert, then Albertshould measure his clock as
ticking slower -- and thus Henrik isthe one who should be younger.
But this is not what happens.*

*So
what's wrong with our analysis? The key point here is thatthe
symmetry was broken. Albert did something that Henrik didnot --
Albert accelerated in turning around. Henrik did noaccelerating, as
he and all the other people on the Earth canattest to (neglecting
gravity). So Albert broke the symmetry, andwhen he returns, he is
the younger one.*

**Ultraviolet
catastrophe**

*A
shortcoming of the Rayleigh-Jeans formula, which attempted todescribe
the radiancy of a blackbody at various frequencies of
theelectromagnetic spectrum. It was clearly wrong because as
thefrequency increased, the radiancy increased without
bound;something quite not observed; this was dubbed the
"ultravioletcatastrophe." It was later reconciled and
explained by theintroduction of Planck's radiation law.*

**Universal
constant of gravitation; G**

*The
constant of proportionality in Newton's law of universalgravitation
and which plays an analogous role in A. Einstein'sgeneral relativity.
It is equal to 6.664*^{.}*10*^{-11}*
N*^{.}*m*^{2}*/kg*^{2}*.*

**V****an
der Waals force (J.D. van der Waals)**

*Forces responsible for the non-ideal behavior of gases, and forthe
lattice energy of molecular crystals. There are three
causes:dipole-dipole interaction; dipole-induced dipole moments;
anddispersion forces arising because of small instantaneous dipolesin
atoms.*

**Wave-particle
duality**

*The
principle of quantum mechanics which implies that light (and,indeed,
all other subatomic particles) sometimes act like a wave,and sometime
act like a particle, depending on the experiment youare performing.
For instance, low frequency electromagneticradiation tends to act
more like a wave than a particle; highfrequency electromagnetic
radiation tends to act more like aparticle than a wave.*

**Widenmann-Franz
law**

*The
ratio of the thermal conductivity of any pure metal to itselectrical
conductivity is approximately constant for any giventemperature.
This law holds fairly well except at lowtemperatures.*

**Wien's
displacement law**

*For
a blackbody, the product of the wavelength corresponding tothe
maximum radiancy and the thermodynamic temperature is aconstant. As
a result, as the temperature rises, the maximum ofthe radiant energy
shifts toward the shorter wavelength (higherfrequency and energy) end
of the spectrum.*

**Woodward-Hoffmann
rules**

*Rules
governing the formation of products during certain types oforganic
reactions.*

**Young's
experiment; double-slit experiment (T. Young; 1801)**

*A
famous experiment which shows the wave nature of light (andindeed of
other particles). Light is passed from a small sourceonto an opaque
screen with two thin slits. The light is refractedthrough these
slits and develops an interference pattern on theother side of the
screen.*

**Zeeman
effect; Zeeman line splitting (P. Zeeman; 1896)**

*The
splitting of the lines in a spectrum when the source is**
**exposed to a magnetic field.*

**Used
Literature***.*

*«Basic Postulats» by Gabrele O’Hara*

*«Elementary Physic For Students» by Bill Strong*

*«Atomic Physic» by Steve Grevesone*

*«Optica» by Steve Grevesone*

*«Thermodynamic’s Laws» by Kay Fedos*

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