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McGraw Hill Financial, Inc. is an American publicly traded corporation headquartered in Rockefeller Center in New York City. Its primary areas of business are financial, publishing, and business services.
A condition that is generic to all physical systems that use the amplification of signals, power, or energy in various forms. Electrical circuits are perhaps the best-known example because the use of amplification is very common there. In order for instability to occur, a closed (circular) path must exist, and the net amplification around it must be sufficiently large that any random signal (for example, noise) that travels around the closed path grows uncontrollably. The condition is eventually limited by some physical aspect of the system such as nonlinearity, saturation, or power available. The energy to create the uncontrollable signal growth is obtained by conversion from some other form of energy. For example, a high-frequency electrical oscillation can draw its energy from a direct- current (dc) power supply.
Industry:Science
A conducting disk with concentric inner and outer electrical contacts, which can be placed in a magnetic field parallel to its axis. The disk is named after O. M. Corbino, who in 1911 reported magnetoresistance measurements on several metals by using this configuration. In zero applied field the lines of current are simply radial (<b>illus.</b> <i>a</i>), but in the presence of an axial magnetic field they lengthen by spiraling (illus. <i>b</i>). This spiraling occurs because the geometry of the disk is such that the Lorentz force acting on the charge carriers is not counterbalanced by a Hall-effect electric field. The resistance of the disk increases as the field increases, largely as a result of the geometrical magnetoresistance effect associated with the lengthening of the current path.
Industry:Science
A conjectured enhanced symmetry of the laws of nature that would relate two fundamental observed classes of particles, bosons and fermions.
Industry:Science
A consequence of the quantum mechanics of interacting identical particles that is responsible for magnetic interactions between electrons and atoms in solids, and magnetic order such as ferromagnetism and antiferromagnetism. The exchange interaction is actually not one of the fundamental interactions such as electromagnetism, but an effect that arises from the interplay of electromagnetism with quantum mechanics.
Industry:Science
A constant designated <i>E</i>, the ratio of stress to corresponding strain when the material behaves elastically. Young's modulus is represented by the slope <i>E</i> = Δ<i>S</i>/Δε of the initial straight segment of the stress-strain diagram. More correctly, <i>E</i> may be represented as the slope of the tangent or the slope of the secant connecting two points of the stress-strain curve. The modulus is then designated as tangent modulus or secant modulus at stated values of stress. The modulus of elasticity applying specifically to tension is called Young's modulus. Many materials have the same value in compression.
Industry:Science
A constant intrinsic to a body which determines its inertial and energy-momentum properties. It is a fundamental concept of special relativity, and in particular it determines the internal energy content of a body. It is the same as the inertial mass of classical mechanics. According to the principle of equivalence, the basic physical principle of general relativity, the inertial mass of a body is also equal to its gravitational mass.
Industry:Science
A constant occurring in practically all statistical formulas and having a numerical value of 1.3807 × 10<sup>-23</sup> joule/K. It is represented by the letter <i>k</i>. If the temperature <i>T</i> is measured from absolute zero, the quantity <i>kT</i> has the dimensions of an energy and is usually called the thermal energy. At 300 K (room temperature), <i>kT</i> = 0.0259 eV.
Industry:Science
A constellation named for the queen of Ethiopia, who, in Greek mythology, claimed to be more beautiful than the Nereids, daughters of the sea god, Poseidon. Poseidon sent a sea monster, Cetus, in revenge, and Cassiopeia's daughter Andromeda was sacrificed to appease the monster. (In some versions of the myth, Cassiopeia boasted of Andromeda's beauty.) However, Andromeda was rescued by Perseus. The constellations named after these figures are adjacent in the sky.
Industry:Science
A constituent electric circuit of a switching or digital data-processing system which receives, stores, or manipulates information in coded form to accomplish the specified objectives of the system. Examples include digital computers, dial telephone systems, and automatic accounting and inventory systems.
Industry:Science
A constituent of matter consisting of <i>z</i> negatively charged electrons bound predominantly by the Coulomb force to a tiny, positively charged nucleus consisting of <i>Z</i> protons and (<i>A</i> - <i>Z</i>) neutrons. <i>Z</i> is the atomic number, and <i>A</i> is the mass or nucleon number. The atomic mass unit is u = 1.661 × 10<sup>-27</sup> kg.
Industry:Science
