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Impedance (Z):

The total opposition that a circuit offers to the flow of alternating current or any other varying current at a particular frequency. It is a combination of resistance R and reactance X, expressed in ohms and designated by Z.

Infrared (Fiber Optic):

Light with wavelengths 700-1000 nm, invisible to the eye, and felt as heat.

Inner Conductor:

The central conductive member in a coaxial structure, such as the center contact in a coaxial connector.

Insert:

That part which holds the contacts in their proper arrangements and electrically insulates them from each other and from the shell. Also called dielectric, insulator, or dielectric support.

Insert Retention:

The axial load in either direction that an insert must withstand without being dislocated from its normal position in the connector shell.

Insertion Loss:

The loss in load power resulting from the insertion of a cable, component, or device. It is expressed in decibels as the ratio of power received at the load before insertion to the power received at the load after insertion.

Insertion Tool:

A small, hand-held tool used to insert contacts into a connector.

Insulation:

A material which offers high electrical resistance, making it suitable for covering components, terminals, and wires. This prevents the possible future contact of adjacent conductors resulting in a short circuit.

Insulation Resistance:

The ratio of the applied voltage to the total current between two electrodes in contact with a specific insulator.

Interface:

(1) A shared boundary;(2) The two surfaces on the contact side of both halves of a multiple-contact connector that face each other when the connector is assembled; (3) In fiber optics, the surface where two materials meet, as in core-cladding interface, or fiber-to-fiber interface in a connector.

ISO:

Abbreviation for International Organization for Standardization.