. The principles of physics. Fig. 442. lines of force of the earth effects a change of the number oflines of force passing through it, as may be understood byinspection of Pig. 443, and this creates temporary currentsin the coil. By examination of Fig. 443 it will be seen that there arein each complete rotation of the coil two points (as A in thefigure) where the coil enclosesa maximum number of lines offorce. In this position the in-duced current vanishes, for atthis instant the number oflines is neither increasing nordiminishing. As the coil inits rotation approaches thesepoints, the number
. The principles of physics. Fig. 442. lines of force of the earth effects a change of the number oflines of force passing through it, as may be understood byinspection of Pig. 443, and this creates temporary currentsin the coil. By examination of Fig. 443 it will be seen that there arein each complete rotation of the coil two points (as A in thefigure) where the coil enclosesa maximum number of lines offorce. In this position the in-duced current vanishes, for atthis instant the number oflines is neither increasing nordiminishing. As the coil inits rotation approaches thesepoints, the number of lines offorce increases, and after leav- yie. 552 ETHER DYNAMICS. ing it the number diminishes. This will evidently cause achange in the direction of the induced current twice duringeach revolution. If then by means of a cow/tmitator, a (), the direction of the current in the galvanometer bechanged relatively to its direction in the coil at each halfrevolution, we have an intermittent current constant in direc-tion through the galvanometer. 519. Lenzs law. — Recurring to the primary and secondarycircuits we remark that the motion of the one or the othermay be in arcs of circles or in any way, yet the motion mayalways be resolved so as to give a resultant indicating ap-proach or recession. The law by which the direction of theinduced current is determined is known as Lenzs law, andmay be expressed as follows : In all cases of induction thedirection of the induced ciorrent is such as to oppose the motionwhich piroduces it. Thus approach develops an opposite cur-rent, since opposite currents resist approach, while recession
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectphysics, bookyear1895
