Electronics Glossary – J

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Term Definition
jack A connecting device into which a plug can be inserted to make circuit connections.
Jacket 1.) A material covering over a wire or cable assembly. 2.) Outer covering of a dual-wall heat-shrinkable tubing.
jackscrew (connector/accessory) A mechanical fastening device (one or two per connector) used to draw mating connectors together and to separate them. Includes a threaded screw on one connector that engages a threaded bushing on the mating connector.
JAN specification Joint Army-Navy specification.
jitter Short-term variation of pulses from their ideal position in time.
Jones block Jones is the name of the originator of barrier blocks. The term “Jones block” is sometimes erroneously used to describe terminal strips and barrier blocks in general.
Joule A unit of energy or work, equal to one watt of power applied for one second. In more fundamental units, a joule is defined as the work required to move an object one meter while applying a force of one newton (N), where a newton is the force required to accelerate a one kilogram mass at one meter per square second.
jumper (1) A direct electrical connection, which is not a portion of the conductive pattern, between two points on a printed circuit. (2) Usually unjacketed twisted pair wire used to make a cross connection.
Junction The plane in a semiconductor device where two layers that have opposing-polarity dopants physically meet.