What is...

Jib Jab Media
A business launched in 1999, by Gregg and Evan Spiridellis from their garage in Brooklyn.

Jominy Hardenability (Quench) Test
The Jominy Test involves heating a test piece from the steel (25mm diameter and 100mm long) to an austenitising temperature and quenching from one end with a controlled and standardised jet of water.

Joule's Law
Physics: The principle that the heat produced by an electric current is equal to the product of the resistance of the conductor, the square of the current, and the time for which it flows.