induction

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. The act or an instance of inducting.
2. n. A ceremony or formal act by which a person is inducted, as into office or military service.
3. n. Electricity The generation of electromotive force in a closed circuit by a varying magnetic flux through the circuit.
4. n. Electricity The charging of an isolated conducting object by momentarily grounding it while a charged body is nearby.
5. n. Logic The process of deriving general principles from particular facts or instances.
6. n. Logic A conclusion reached by this process.
7. n. Mathematics A two-part method of proving a theorem involving an integral parameter. First the theorem is verified for the smallest admissible value of the integer. Then it is proven that if the theorem is true for any value of the integer, it is true for the next greater value. The final proof contains the two parts.
8. n. The act or process of inducing or bringing about, as:
9. n. Medicine The inducing of labor, whereby labor is initiated artificially with drugs such as oxytocin.
10. n. Medicine The administration of anesthetic agents and the establishment of a depth of anesthesia adequate for surgery.
11. n. Biochemistry The process of initiating or increasing the production of an enzyme, as in genetic transcription.
12. n. Embryology The process by which one part of an embryo causes adjacent tissues or parts to change form or shape, as by the diffusion of hormones or other chemicals.
13. n. Presentation of material, such as facts or evidence, in support of an argument or proposition.
14. n. A preface or prologue, especially to an early English play.

Century Dictionary and Cyclopedia

1. n. The act of inducting or bringing in.
2. n. Specifically, the introduction of a person into an office with the customary forms and ceremonies; installation; especially, the introduction of a clergyman into a benefice, or the official act of putting a clergyman in actual possession of the church and its temporalities, to which he has been presented: usually performed by virtue of a mandate under the seal of the bishop.
3. n. Beginning; commencement; introduction.
4. n. In a literary work, an introduction or preface; a preamble; a prologue; a preliminary sketch or scene; a prelude, independent of the main performance, but exhibiting more or less directly its purpose or character: as, the induction to Shakspere's “Taming of the Shrew.”
5. n. In logic, the process of drawing a general conclusion from particular cases; the inference from the character of a sample to that of the whole lot sampled. Aristotle's example is: Man, the horse, and the mule are animals lacking a gall-bladder; now, man, the horse, and the mule are long-lived animals; hence, all animals that lack the gall-bladder are long-lived. Logicians usually make it essential to induction that it should be an inference from the possession of a character by all the individuals of the sample to its possession by the whole class; but the meaning is to be extended so as to cover the case in which, from the fact that a character is found in a certain proportion of individuals of the sample, its possession by a like proportion of individuals of the whole lot sampled is inferred. Thus, if one draws a handful of coffee from a bag, and, finding every bean of the handful to be a fine one, concludes that all the beans in the bag are fine, he makes an induction; but the character of the inference is essentially the same if, instead of finding that all the beans are fine, he finds that two thirds of them are fine and one third inferior, and thence concludes that about two thirds of all the beans in the bag are fine. On the other hand, induction, in the strict sense of the word, is to be distinguished from such methods of scientific reasoning as, first, reasoning by signs, as, for example, the inference that because a certain lot of coffee has certain characters known to belong to coffee grown in Arabia, therefore this lot grew in Arabia; and, second, reasoning by analogy, where, from the possession of certain characters by a certain small number of objects, it is inferred that the same characters belong to another object, which considerably resembles the objects named, as the inference that Mars is inhabited because the earth is inhabited. But the term induction has a second and wider sense, derived from the use of the term inductive philosophy by Bacon. In this second sense, namely, every kind of reasoning which is neither necessary nor a probable deduction, and which, though it may fail in a given case, is sure to correct itself in the long run, is called an induction. Snch inference is more properly called ampliative inference. Its character is that, though the special conclusion drawn might not be verified in the long run, yet similar conclusions would be, and in the long run the premises would be so corrected as to change the conclusion and make it correct. Thus, if, from the fact that female births are generally in excess among negroes, it is inferred that they will be so in the United States during any single year, a probable deduction is drawn, which, even if it happens to fail in the special case, will generally be found true. But if, from the fact that female births are shown to be in excess among negroes in any one census of the United States, it is inferred that they are generally so, an induction is made, and if it happens to be false, then on continuing that sort of investigation, new premises will be obtained from other censuses, and thus a correct general conclusion will in the long run be reached. Induction, as above defined, is called philosophical or real induction, in contradistinction to formal or logical induction, which rests on a complete enumeration of cases and is thus induction only in form. A real induction is never made with absolute confidence, but the belief in the conclusion is always qualified and shaded down. Socratic induction is the formation of a definition from the consideration of single instances. Mathematical induction, so called, is a peculiar kind of demonstration introduced by Fermat, and better termed Fermatian inference. This demonstration, which is indispensable in the theory of numbers, consists in showing that a certain property, if possessed by any number whatever, is necessarily possessed by the number next greater than that number, and then in showing that the property in question is in fact possessed by some number, N; whence it follows that the property is possessed by every number greater than N.
6. n. In physics, the process by which a body having electrical or magnetic properties calls forth similar properties in a neighboring body without direct contact; electrical influence. Statical or electrostatic induction is the production of an electrical charge upon a body by the influence of another body which is charged with statical electricity. For example, if a brass sphere A charged with electricity is brought near to a neutral conductor B, it calls forth or induces in it a state of electrification opposite to that of A on the nearer end a, and of the same kind on b. The presence of electricity on the surface of B may be shown by the divergence of the pith balls. The electricity at a is bound by the charge on A, while that at b is free. If a ground connection is made, as by touching B with the finger, that at b will pass off, leaving only the opposite kind of electricity on B, which, if the sphere A is removed, will then diffuse itself over the whole surface and be free, B becoming charged by induction with negative electricity if that of A be positive. It can be shown by experiment that the inductive influence is transmitted through the non-conducting medium, which may be considered as in a state of strain or tension. It is found, further, that the character of the medium determines the amount of induced electricity. The power of a non-conducting substance to transmit this influence, as compared with that of dry air, is called its specific inductive capacity, or dielectric capacity. For example, for glass it is several times that of dry air. The principle of statical induction is involved in the electrophorus, in the Holtz and other influence or induction machines, and in the condenser, as in the Leyden jar. Voltaic or electrodynamic induction is the production of an electric current by the influence of another independent current. When the current is induced by the action of a magnet, or when a magnetic condition is induced by an electric current, the phenomenon is spoken of as electromagnetic induction. Suppose we have a small coil or bobbin of rather coarse insulated copper wire connected with a voltaic battery, called the primary coil, A, and another larger hollow coil of finer wire, also insulated, called the secondary coil, B, whose poles are connected with a galvanometer. It will be found that if A is first inserted within B, and then a current is sent through A, at the instant when the circuit is made a momentary current (induced current) will be induced in B, opposite in direction to that of A; also that, when the primary circnit is broken, there will be a momentary induced current in the same direction as that in A—that is, a direct current will be induced in B. If, further, the primary current is rapidly made and broken, the wire of the secondary coil will be continually traversed by a current, but one whose direction is continually alternating. A similar result will be produced if the primary current is varied rapidly in strength, an increase in strength producing an inverse, and a decrease a direct current. Thirdly, if while A is continually traversed by a current it is first inserted within B and then withdrawn, an induced current will be caused in B, first inverse and on the withdrawal direct, and so on. Similarly, if a magnet is first introduced within B and then withdrawn, the result is to induce in B a current respectively inverse and direct to the amperian currents of the magnet considered as a solenoid. (See Ampère's theory, under theory.) Again, if a piece of soft iron is placed within the coil B, and a magnet is rapidly approached and withdrawn from it, the effect (see magnetic induction, below) is to magnetize the soft iron, and with the approach of the magnet this magnetism increases in strength, and (analogous to case 3, above) a current inverse to the amperian current is induced, and conversely when the magnet is taken away. The principles of voltaic and electromagnetic induction are used in the induction-coil (which see), in all magneto-electric and dynamo-electric machines (see under electric), and also in the telephone (which see), and in many other devices. Induced currents can be made to have a very high electromotive force, it being in many cases comparable with that produced by a Holtz machine; but this depends upon the relative fineness of the wire of the secondary coil as compared with that of the primary coil. An electric current may also induce (as when it is made and broken) a current, called an extra current, in the conductor through which it itself passes; this is called self-induction. Magnetic induction is the production of magnetic properties in a magnetic substance, as a bar of soft iron, by a neighboring magnet. The effect of the magnet is to develop the magnetic polarity of each molecule of the soft iron, and hence to make the whole bar a magnet, with poles reversed as compared with the inducing magnet. If several pieces of soft iron are placed near together, the inductive effect is transmitted from the first to the second, and so on. The magnetic induction in a magnet, or magnetic medium, is the force which would exist within a narrow crevice cut out of the magnet with its plane sides normal to the direction of force. See magnetic.
7. n. Magnetic induction is the flux density in a medium such as iron when subjected to a magnetizing force. It is expressed in terms of a unit called the gauss, namely, the number of lines of force per square centimeter of cross-section of the substance. Induction, thus numerically defined, is usually designated by the letter B; the magnetizing force to which it is due, by the letter H. Induction is frequently determined by winding a ring-shaped piece of the iron to be tested with two coils of wire, the primary and the secondary coil. The secondary coil is connected to a ballistic galvanometer and a known current is suddenly sent through the primary coil. The magnetic field thus established within the iron induces a flow of electricity through the secondary coil and through the galvanometer, which affords a measure of the induction. The relation is expressed by the equation where Q is the quantity of electricity as measured by the deflection of the galvanometer, R is the resistance of the secondary circuit, S is the cross-section of the iron, and n₂ is the number of turns of wire in the secondary coil. The relation between induction and the magnetizing force may be expressed graphically by means of a curve, called the curve of induction, in which ordinates represent the values of the induction B and abscissæ the corresponding values of the magnetizing force H. The curve rises slowly for small magnetizing forces and then sharply, for a time, until the iron approaches saturation, after which the slope of the curve diminishes. These changes in the direction of the curve are due to variations in the permeability of the iron, which increases with the magnetizing force, reaches a maximum, and then diminishes again indefinitely. The induction B is not identical with the magnetization I which is defined by the equation
8. n. The leading or admission of steam into a cylinder.
9. n. In general, the principle that, given any class of terms s, to which belongs the first term of any progression, and to which belongs the term of the progression next after any term of the progression belonging to s, then every term of the progression belongs to s.

Wiktionary

1. n. the act of inducing childbirth
2. n. the act of inducting
3. n. a formal ceremony in which a person is appointed to an office or into military service
4. n. physics the generation of an electric current by a varying magnetic field
5. n. logic the derivation of general principles from specific instances
6. n. mathematics A general proof of a theorem by first proving it for a specific integer (for example) and showing that, if it is true for one integer then it must be true for the next.
7. n. theater The use of rumors to twist and complicate the plot of a play or to narrate in a way that does not have to state truth nor fact within the play.
8. n. biology In developmental biology, the development of a feature from part of a formerly homogenous field of cells in response to a morphogen whose source determines the feature's position and extent.
9. n. obsolete an introduction

GNU Webster's 1913

1. n. The act or process of inducting or bringing in; introduction; entrance; beginning; commencement.
2. n. obsolete An introduction or introductory scene, as to a play; a preface; a prologue.
3. n. (Philos.) The act or process of reasoning from a part to a whole, from particulars to generals, or from the individual to the universal; also, the result or inference so reached.
4. n. The introduction of a clergyman into a benefice, or of an official into a office, with appropriate acts or ceremonies; the giving actual possession of an ecclesiastical living or its temporalities.
5. n. (Math.) A process of demonstration in which a general truth is gathered from an examination of particular cases, one of which is known to be true, the examination being so conducted that each case is made to depend on the preceding one; -- called also successive induction.
6. n. (Physics) The property by which one body, having electrical or magnetic polarity, causes or induces it in another body without direct contact; an impress of electrical or magnetic force or condition from one body on another without actual contact.

WordNet 3.0

1. n. an electrical phenomenon whereby an electromotive force (EMF) is generated in a closed circuit by a change in the flow of current
2. n. a formal entry into an organization or position or office
3. n. stimulation that calls up (draws forth) a particular class of behaviors
4. n. reasoning from detailed facts to general principles
5. n. the act of bringing about something (especially at an early time)
6. n. an act that sets in motion some course of events