Induction Hardening

A surface-hardening process in which only the surface layer of a suitable ferrous workpiece is heated by electromagnetic induction to above the upper critical temperature and immediately quenched.

Induction Heating

Heating by combined electrical resistance and hysteresis losses induced by subjecting a metal to the varying magnetic field surrounding a coil carrying alternating current.

Induction Tempering

Tempering of steel using low-frequency electrical induction heating .

Infrared Analyzer

An atmosphere-monitoring device that measures a gas (usually carbon monoxide, carbon dioxide, and methane) presence based on specific wavelength absorption of infrared energy.

Impedance Match

The condition (for maximum power transfer) when the transmitting impedance equals the receiving impedance, or when a suitable transformer is inserted between different impedances for matching purposes. Also see IMPEDANCE MATCHING.

Inclinometer

An instrument for measuring INCLINATION. One form consists of a magnetic needle mounted so that it can swing inside a vertically mounted circular scale.

Induction Coil

A special high-voltage step-up ransformer having an open core and a vibratorinterrupter in series with the primary winding, which carries direct current from a battery. The current is broken up into short pulses by the interrupter, and a high alternating-current voltage is generated in the secondary winding.

Image Rejection

In a superheterodyne radio receiver, the suppression or elimination of IMAGE INTERFERENCE by means of a selective circuit, such as a radio-frequency preamplifier.

Image Antenna

An imaginary “mirror” antenna below the effective radio-frequency (RF) ground surface, at a depth equal to the height of the true radiating antenna above effective RF ground.