Lamp (electrical component)

A lamp is a replaceable component such as an incandescent light bulb, which is designed to produce light from electricity. These components usually have a base of ceramic, metal, glass or plastic, which makes an electrical connection in the socket of a light fixture. This connection may be made with a screw-thread base, two metal pins, two metal caps or a bayonet cap. Re-lamping is the replacement of only the removable lamp in a light fixture.

Lamp circuit symbols

In circuit diagrams lamps usually are shown as symbols. There are two main types of symbols, these are:

The cross in a circle, which usually represents a lamp as an indicator.  
The semicircular dent in a circle, which usually represents a lamp as a source of light or illumination.