| 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. |
