INDUCTION. if an electrified body is brought near an uncharged one—either conductor or non-conductor—the latter will exhibit electri cal forces: ii i.s said to be charged by 'induction.' In general, if a charged body is surrounded by a uniform medium, such as air, and if a body of any other material than that of the medium is introduced, thus leaking the surrounding medium Heterogeneous, there will be induced charges on I he body introduced. The question as to the character of the charges on this body and their distribution depends upon the relative electrical inductivity of the body and the surrounding me dium. (See ELECTRICITY.) Similarly, if there is a magnet surrounded by a uniform medium, such as air, rind if a body of a different kind of material from the medium is brought near the magnet, it will exhibit magnetic forces and is said to be magnetized by induction. The charac
ter and distribution of this induced magnetiza tion depend upon the relative magnetic induc tivity of the medium and the foreign body. (See AIAGNErtsxt.) If the body which is introduced is iron or any magnetic body, and if the medium is air, the induced magnetization is such as to produce attraction by the magnet; if bismuth is introduced there will be repulsion. Electro magnetic induction is the phenomenon observed when the magnetie field of force included by a conducting circuit is altered in any way, viz. eke trie currents are produced in this circuit. These induced currents are due to the elmnging of the field of magnetic force, and are in such a direc tion as to tend to neutralize the change: they last only so long as the field is changing. See EtErrui