An arc lamp or arc light is a lamp that produces light by an electric arc.
The 15 kW xenon short-arc lamp used in the IMAX projection system.
A mercury arc lamp from a fluorescence microscope.
A krypton long arc lamp (top) is shown above a xenon flashtube. The two lamps, used for laser pumping, are very different in the shape of the electrodes, in particular, the cathode (on the left).
A krypton arc lamp during operation.
An electric arc is an electrical breakdown of a gas that produces a prolonged electrical discharge. The current through a normally nonconductive medium such as air produces a plasma, which may produce visible light. An arc discharge is initiated either by thermionic emission or by field emission. After initiation, the arc relies on thermionic emission of electrons from the electrodes supporting the arc.
An arc discharge is characterized by a lower voltage than a glow discharge. An archaic term is voltaic arc, as used in the phrase "voltaic arc lamp".
An electric arc between two nails
Natural lightning is now considered an electric spark, not an arc.
Electricity arcs between the power rail and electrical pickup "shoe" on a London Underground train
Electric arc between strands of wire.
