AWM
Appliance Wiring Material

Jack
A plug-in type terminal widely used in electronic apparatus for temporary connections

Jacket
Pertaining to wire and cable, the outer sheath which protects against the environment and may also provide additional insulation

JAN Specification
Joint Army-Navy Specification (replaced by current Military Specifications)

Jet Starter Cable
Single conductor 600V cable used for external aircraft power

Jitter
The slight movement of a transmission signal in time or phase that can introduce errors and loss of synchronization in high-speed synchronous communications

Joint
That portion of the conductor where the ends of two wires, rods, or groups of wires are joined by brazing, soldering, welding or by mechanical means

Joule's Law
When electricity flows through a material the rate of heating in watts will equal the resistance of the material in ohms times the square of the current amperes. W 5 I²R

Jumper Cable
Extra flexible cables with high-voltage insulation for use as temporary connections. Usually has red jacket