Joule (J)

A unit of energy (1 watt-second) used to describe the rate of energy delivery. It is equal to 1 watt-second or 0.239 calorie.


A unit of radiant exposure used in measuring the amount of energy incident upon a unit area.

Judas Optic

A small defocused Galilean telescope mounted in a hole in a door. Viewed from inside, a wide-angle view of the outside is seen; viewed from outside, the field is narrow, and the image is extremely out of focus.