. The principles of physics. is com-paratively short), and has,of course, little is a long coil of fine wirehaving many turns. CoilA is in circuit with twoBunsen cells in multiple circuit we call theprimary circuit, the currentin this circuit the primaryor inducing current, and thecoil the primary coil. An- DBSCKIPTION OF APPARATUS. 547 other circuit, having in it no battery or other means of gener-ating a current, contains coil B and a galvanoscope with anastatic needle.^ This circuit is called the secondary circuit,the coil the secondary coil, and the currents which cir
. The principles of physics. is com-paratively short), and has,of course, little is a long coil of fine wirehaving many turns. CoilA is in circuit with twoBunsen cells in multiple circuit we call theprimary circuit, the currentin this circuit the primaryor inducing current, and thecoil the primary coil. An- DBSCKIPTION OF APPARATUS. 547 other circuit, having in it no battery or other means of gener-ating a current, contains coil B and a galvanoscope with anastatic needle.^ This circuit is called the secondary circuit,the coil the secondary coil, and the currents which circulatethrough this circuit are called secondary or induced currents. Experiment 1. — After all the connections are made, and a current isestablished in the primary circuit, and the galvanoscope needle is broughtto zero, lower the primary coil quickly into the secondary coil, watchingat the same time the needle of the galvanoscope to see whether it moves,and, it so, in what direction. Simultaneously with this movement there. Fig. 438. is a movement of the needle, showing that a current must have passedthrough the secondary circuit. Let the primary coil rest within, thesecondary, until the needle comes to rest. After a few vibrations theneedle settles at zero, showing that the secondary current was a tem-porary one. Now, watching the needle, quickly pull the primary coilout; another deflection in the opposite direction occurs, showing that acurrent in the opposite direction is caused by withdrawing the coil. It is evident that in this case the current does not by itsmere presence cause an induced current, but that a change inthe relative positions of the two circuits, one of which bearsa current, is necessary. This needle consists of two needles of about the same intensity with their polesreversed, fixed parallel with each other. Though the needles nearly neutralize eachother and are therefore little affected by the field of the earths magnetism, they areespecially seniitive to
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectphysics, bookyear1895
