Faraday’s Principle

—All dynamos, of whatever form, are based upon the discovery made by Faraday in 1831, that electric currents are generated in conductors by moving them in a magnetic field. Faraday’s principle may be enunciated as follows: ‘‘When a conductor is moved in a field of magnetic force in any way so as to cut the lines of force, there is an electromotive force produced in the conductor, in a direction at right angles to the direction of the motion, and at right angles also to the direction of the lines of force, and to the right of the lines of force, as viewed from the point from which the motion originates.” In other words, Faraday’s principle may be thus stated: If a wire be moved near a magnet acro a space in which there are magnet lines, the motion of the wire, as it cuts acro those magnetic lines, sets up magnetic whirls round the moving wire, that is, generates a so called current of electricity in that wire. It is, however, nece ary that the moving conductor should, in its motion, so cut the magnetic lines as to alter the number of lines of force that pa through the circuit of which the moving conductor forms part. f a conducting circuit, a wire ring or single coil, for example, be moved along in a uniform magnetic field, so that only the same lines of force pa through it, no current will be generated.