These conditions are satisfied by using in the impedance coil many turns of large wire and an ample iron core.
What is the impedance if the voltage of the line is 115 volts?
The impedance coils are wound on insulating rods, which hold them near, but not touching, the ground carbon.
The usual diagrammatic symbol for an impedance coil is shown in Fig. 106.
Each Morse circuit will be seen to include, serially, two 50-ohm impedance coils, and to have shunts through condensers to ground.
These four impedance coils are wound on separate cores and do not have any inductive relation whatsoever with each other.
The battery supply to the operator's transmitter is through an impedance coil 9.
In order to further increase the impedance, the cores are made long and heavy.
In applying Ohm's law to an alternating current circuit, impedance must be substituted for resistance.
The impedance these windings offer to the high frequency of lightning oscillations is great.
A measure of the opposition to the flow of alternating current through a circuit. Impedance is measured in ohms. The resistance of a circuit to direct current (also measured in ohms) is generally not the same as its impedance, due to the effects of capacitance and induction in and among the components of the circuit. See also impedance matching.