LAWS
OF PHYSICS
(A to Z)
- The basic laws of physics fall into two categories: classical physics that deals with the observable world (classical mechanics), and atomic physics that deals with the interactions between elementary and sub atomic particles (quantum mechanics).
- The basic laws of both are listed here in alphabetical order. Some laws apply only to one or the other category; some belong to both.
- A few of the laws listed may have little impact on petrophysics and some may have been left off the list for any number of reasons.
Ampere's
Law
The line integral of the magnetic
flux around a closed curve is proportional to the algebraic sum of electric
currents flowing through that closed curve; or, in differential form curl B
= J.
Archimedes' Principle
Avogadro's Hypothesis (1811)
Bernoulli's Equation
Biot-Savart Law
A law
which describes the contributions to a magnetic field by an electric current.
It is analogous to Coulomb's
law.
Boyle's Law (1662); Mariotte's law (1676)
Bragg's Law (1912)
The continuous random motion of solid microscopic particles when
suspended in a fluid medium due to the consequence of ongoing bombardment by
atoms and molecules.
A quantum mechanical effect, where two very large plates placed close to
each other will experience an attractive force, in the absence of other forces.
The cause is virtual particle-antiparticle pair creation in the vicinity of the
plates. Also, the speed of light will be increased in the region between the
two plates, in the direction perpendicular to them.
The principle that cause must
always preceed effect. More formally, if an event A ("the
cause") somehow influences an event B ("the effect")
which occurs later in time, then event B cannot in turn have an
influence on event A. That is, event B must occur at a later time
t than event A, and further, all frames must agree upon this
ordering.
A pseudoforce on an object when it is moving in
uniform circular motion. The "force" is directed outward from the
center of motion.
Charles' Law (1787)
Radiation emitted by a massive particle which is moving faster than light
in the medium through which it is traveling. No particle can travel faster than
light in vacuum, but the speed of light in other media, such as water, glass,
etc., are considerably lower. Cherenkov radiation is the electromagnetic
analogue of the sonic boom, though Cherenkov radiation is a shockwave set up in
the electromagnetic field.
The principle that a given system cannot exhibit both wave-like behavior
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 a system, but no experiment will reveal both
simultaneously.
An effect that demonstrates that
photons (the quantum of electromagnetic radiation) have momentum. A photon fired
at a stationary particle, such as an electron, will impart momentum to the
electron and, since its energy has been decreased, will experience a
corresponding decrease in frequency.
The total mass-energy of a closed system remains constant.
The total electric charge of a closed system remains constant.
The total linear momentum of a closed system remains constant.
The total angular momentum of a
closed system remains constant.
There are several other laws that
deal with particle physics, such as conservation of baryon number, of
strangeness, etc., which are conserved in some fundamental interactions (such
as the electromagnetic interaction) but not others (such as the weak interaction).
One of the postulates of A.
Einstein's special theory of relativity, which puts forth that the speed of light in vacuum is measured as the same speed to all observers,
regardless of their relative motion.
An equation which states that a
fluid flowing through a pipe flows at a rate which is inversely proportional to
the cross-sectional area of the pipe. It is in essence a restatement of the
conservation of mass during constant flow.
The idea, suggested by Copernicus,
that the Sun, not the Earth, is at the center of the Universe. We now know that
neither idea is correct.
Coriolis Pseudoforce (1835)
A pseudoforce which
arises because of motion relative to a frame of reference which is itself
rotating relative to a second, inertial frame. The magnitude of the Coriolis
"force" is dependent on the speed of the object relative to the
noninertial frame, and the direction of the "force" is orthogonal to
the object's velocity.
The principle that when a new,
more general theory is put forth, it must reduce to the more specialized (and
usually simpler) theory under normal circumstances. There are correspondence
principles for general relativity to special relativity and special relativity
to Newtonian mechanics, but the most widely known correspondence principle is
that of quantum mechanics to classical mechanics.
Coulomb's Law
The primary law for
electrostatics, analogous to Newton's law of universal
gravitation. It states that the force between two point charges is proportional
to the algebraic product of their respective charges as well as proportional to
the inverse square of the distance between them.
Curie's Law
Curie-Weiss Law
A more general form of Curie's Law, which states that the susceptibility of a paramagnetic
substance is related to its thermodynamic temperature T by the equation KHI = C/T - W, where W is the Weiss constant.
Dalton's
Law of partial pressures
Waves emitted by a moving object as received by an observer will be
blueshifted (compressed) if approaching, redshifted (elongated) if receding. It
occurs both in sound as well as electromagnetic phenomena.
Dulong-Petit Law (1819)
The cornerstone of Einstein's general theory of
relativity, relating the gravitational tensor G to the
stress-energy tensor T by the simple equation G = 8 pi T.
stress-energy tensor T by the simple equation G = 8 pi T.
The energy E of a particle is equal to its mass M
times the square of the speed of light c, giving rise to the best known physics
equation in the Universe: E = M c2.
The basic postulate of A. Einstein's general theory
of relativity, which posits that an acceleration is fundamentally
indistinguishable from a gravitational field.
Faraday's
Law
Faraday's Laws of electrolysis
The amount of chemical change
during electrolysis is proportional to the charge passed.
The charge Q required to
deposit or liberate a mass m is proportional to the charge z of
the ion, the mass, and inversely proportional to the relative ionic mass M;
mathematically Q = F m z / M,
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.
The sense of the induced
electromotive force depends on the direction of the rate of the change of the
field.
The principle states that the path taken by a ray of
light between any two points in a system is always the path that takes the
least time.
Gauss' Law for magnetic fields
The magnetic flux through a closed
surface is zero; no magnetic charges exist; in differential form
div B = 0.
div B = 0.
When charged particles flow through a tube which has both an electric
field and a magnetic field (perpendicular to the electric field) present in it,
only certain velocities of the charged particles are preferred, and will make
it un-deviated through the tube; the rest will be deflected into the sides.
Hooke's Law
Huygens' Principle
Joule-Thomson
Effect; Joule-Kelvin Effect
The heat Q produced when a
current I flows through a resistance R for a specified time t
is given by Q = I2 R t .
The sum of the potential
differences encountered in a round trip around any closed loop in a circuit is
zero.
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
Lambert's Laws
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.
If the rays meet the surface at an
angle, then the illuminance is proportional to the cosine of the angle with the
normal.
The luminous intensity of light
decreases exponentially with distance as it travels through an absorbing
medium.
For steady-state heat conduction in one dimension, the temperature
distribution is the solution to Laplace's equation, which states that the
second derivative of temperature with respect to displacement is zero.
Lenz's Law (1835)
The ratio of the speed of an object in a given medium to the speed of
sound in that medium.
Mach's Principle (1870)
Gauss' law
The electric flux through a closed
surface is proportional to the algebraic sum of electric charges contained
within that closed surface; in differential form div E = rho, where
rho is the charge density.
Gauss' law for magnetic fields
The magnetic flux through a closed
surface is zero; no magnetic charges exist. In differential form div B =
0.
Faraday's law
The line integral of the electric
field 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; in
differential form curl E = -dB/dt,..
The line integral of the magnetic field 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 differential form curl H = J + dD/dt,.
In addition to describing electromagnetism, his equations also predict
that waves can propagate through the electromagnetic field, and would always
propagate at the the speed of light in vacuum.
Murphy's Law (1942)
Newton's Law of universal gravitation
Two bodies attract each other with
equal and opposite forces; the magnitude of this force is proportional to the
product of the two masses and is also proportional to the inverse square of the
distance between the centers of mass of the two bodies; F = (G m M/r2) e, where
m and M are the masses of the two bodies, r is the
distance between. the two, and e is a unit vector directed from the test mass
to the second.
Newton's Laws of motion
A body continues in its state of
constant velocity (which may be zero) unless it is acted upon by an external
force.
For an unbalanced force acting on
a body, the acceleration produced is proportional to the force impressed; the
constant of proportionality is the inertial mass of the body.
In a system where no external
forces are present, every action force is always opposed by an equal and
opposite reaction force.
Occam's
Razor (1340)
Ohm's Law (1827)
Pascal's
Principle
In a hierarchy, every employee tends to rise to his level of incompetence.
For a wavefront intersecting a reflecting surface, the angle of incidence
is equal to the angle of reflection, in the same plane defined by the ray of
incidence and the normal.
For a wavefront traveling through a boundary between two media, the first
with a refractive index of n1, and the other with one of n2,
the angle of incidence theta is related to the angle of refraction phi
by n1 sin theta = n2 sin phi.
The principle, employed by Einstein's relativity
theories, that the laws of physics are the same, at least qualitatively, in all
frames. That is, there is no frame that is better (or qualitatively any
different) from any other. This principle, along with the constancy principle, constitute the founding
principles of special relativity.
Stefan-Boltzmann
Law
The
radiated power P (rate of emission of electromagnetic energy) of a hot
body is proportional to the radiating surface area, A, and the fourth
power of the thermodynamic temperature, T. The constant of
proportionality is the Stefan-Boltzmann constant. Mathematically P = e sigma A T4,.where
the efficiency rating e is called the emissivity of the object.
The general idea that, when a number of influences
are acting on a system, the total influence on that system is merely the sum of
the individual influences; that is, influences governed by the superposition
principle add linearly.
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.
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.
For changes involving only perfect
crystalline solids at absolute zero, the change of the total entropy is zero.
If two bodies are each in thermal
equilibrium with a third body, then all three bodies are in thermal equilibrium
with each other.
A principle, central to quantum mechanics, which
states that two complementary parameters (such as position and momentum, energy
and time, or angular momentum and angular displacement) cannot both be known to
infinite accuracy; the more you know about one, the less you know about the
other.
Forces responsible for the non-ideal behavior of
gases, and for the lattice energy of molecular crystals. There are three
causes: dipole-dipole interaction; dipole-induced dipole moments; and
dispersion forces arising because of small instantaneous dipoles in atoms.
Wave-Particle Duality
Wiedemann-Franz
Law
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