The laws list
A
 26Lw1 Laws

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
A.
aberration
The apparent change in position of a light-emitting object due to the constancy of the speed of light and the motion of the observer relative to the emitter. The effect is nonrelativistic; that is, special relativity is not required to derive it: all that is needed is Newtonian mechanics and the assumption of the constancy of the speed of light. The effect is observable in the apparent change of position of stars due to Earth's relative motion, and is responsible for the "tunnel vision" effect of travelling at relativistic speeds.
ampere; A (after A.M. Ampere, 1775-1836)
The fundamental SI unit of electric current, defined as the current that, when going through two infinitely-long parallel conductors of negligible cross-section and placed 1 m apart in vacuum, results in a force between the two conductors of 2 x 10-7 N/m.
Ampere's law (A.M. Ampere)
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.
This was later
modified to add a second term when it was incorporated 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, and this process can only happen at certain times through the evolution of any given universe.
strong anthropic principle
A more forceful argument than the weak principle: It implies 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, no intelligent beings would be able to consider the laws of the Universe at all.
Arago spot (D.F.J. Arago)
A bright spot that appears in the shadow of a uniform disc being backlit by monochromatic light emanating from a point source.
Archimedes' principle
A body that is submerged in a fluid is buoyed up by a force equal in magnitude to the weight of the fluid that is displaced, and directed upward along a line through the center of gravity of the displaced fluid.
Atwood's machine
A weight-and-pulley system devised to measure the acceleration due to gravity at Earth's surface by measuring the net acceleration of a set of weights of known mass around a frictionless pulley.
The number of items in a sample of a substance which is equal to the number of atoms or molecules in a sample of an ideal gas which is at standard temperature and pressure. It is equal to about 6.022 52 x 1023 mol-1.
Equal volumes of all gases at the same temperature and pressure contain equal numbers of molecules. It is, in fact, only true for ideal gases.
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