Joint. The point where two or more electric conductors join.
Joint Resistance. The united resistance offered by a number of resistances connected in parallel.
Jumper. A short circuit-shunt employed temporarily around an apparatus, lamp, or motor to cut out the current.
Jump-spark. A disruptive spark excited between two conducting surfaces in distinction from a spark excited by a rubbing contact.
K
Kaolin. A form of earth or product of decomposed feldspar composed of silica and alumina. It is serviceable in insulating compounds.
Kathode. The terminal of an electric circuit whence an electrolyzing current passes from a solution. It is the terminal connected to the zinc pole of a battery or the article on which the electro-deposit is made.
Key. The arm of a telegraphic sounder by which the circuit is made and broken. A pivoted lever with a finger-piece which, when depressed, makes contact between a point and a stationary contact on the base.
Keyboard. A board, or table, on which keys or switches are mounted.
A switchboard.