FIG. 42.—High potential "Humming" transformer.
FIG. 43.—High potential closed core transformer for wireless work.
FIG. 44.—Leyden jar set for oil immersion to prevent losses from brush discharges.
From these facts we may readily see why the troublesome interrupter may be eliminated when alternating current is used. Every time that the current rises and falls the magnetic field changes.
Considerable care must be used in proportioning the windings so that they possess sufficient reactance. Reactance is the tendency of a coil to resist the flow of an alternating current. A reactance coil is sometimes placed in circuit with an open core transformer to prevent the spark from arcing. Arcing is the tendency of the spark to pass across the gap without charging the condenser and creating any high frequency oscillations.
FIG. 45.—Oil immersed condenser