An 'Arc' Lamp ​is atype of lamp which produces light by an electric arc discharge between tow electrode connected to a DC electric supply and uses different materials as the electrodes,withsome lamps also utilsing gasses and some metal elements.

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The carbon arc light, which consists of an arc between carbon electrodes in air, invented by Humphry Davy in the first decade of the 1800s, was the first practical electric-light. It was widely used starting in the 1870s for street and large building lighting until it was superseded by the incandescent lamp in the early 20th century. It continued in use for more specialized applications where a high intensity point light source was required, such as searchlights and movie projectors.

 

The carbon arc lamp is now obsolete for most applications, but it is still used as a source of high intensity ultraviolet light.