HOWLING.--Where more than three stages of radio amplification, or more than two stages of audio amplification, are used howling noises are apt to occur in the telephone receivers.
IMPEDANCE.--An oscillation circuit has reactance and also resistance, and when these are combined the total opposition to the current is called impedance.
INDUCTANCE COILS.--See Coils, Inductance.
INDUCTANCE COIL, LOADING.--See Coil, Loading Inductance.
INDUCTIVE COUPLING.--See Coupling, Inductive.
INDUCTIVE REACTANCE.--See Reactance, Inductive.
INDUCTION COIL.--See Coil, Induction.
INDUCTION, MUTUAL.--Induction produced between two circuits or coils close to each other by the mutual interaction of their magnetic fields.
INSULATION.--Materials used on and around wires and other conductors to keep the current from leaking away.
INSPECTOR, RADIO.--A U. S. inspector whose business it is to issue both station and operators' licenses in the district of which he is in charge.