Lamp (electrical component)

"Electric lamp" and "Light bulb" redirect here. For the item of furniture, see light fixture. For the music by Fujiya & Miyagi, see Lightbulbs (album).

Incandescent (left) and fluorescent (right) lightbulbs turned on

A lamp is a replaceable component that produces light from electricity. Compact lamps are commonly called light bulbs; for example, the incandescent light bulb. Lamps usually have a base made of ceramic, metal, glass or plastic, which secures the lamp in the socket of a light fixture. The electrical connection to the socket may be made with a screw-thread base, two metal pins, two metal caps or a bayonet cap.

Types

There are several types of lamp:

• Incandescent lamp, a heated filament inside a glass envelope
  • Halogen lamps use a fused quartz envelope, filled with halogen gas
• LED lamp, a solid-state lamp that uses light-emitting diodes (LEDs) as the source of light
• Arc lamp
  • Xenon arc lamp
  • Mercury-xenon arc lamp
  • Ultra-high-performance lamp, an ultra-high-pressure mercury-vapor arc lamp for use in projectors
  • Metal-halide lamp
• Gas-discharge lamp, a light source that generates light by sending an electrical discharge through an ionized gas
  • Fluorescent lamp
    • Compact fluorescent lamp, a fluorescent lamp designed to replace an incandescent lamp
  • Neon lamp
  • Mercury-vapor lamp
  • Sodium-vapor lamp
  • Sulfur lamp
  • Electrodeless lamp, a gas discharge lamp in which the power is transferred from outside the bulb to inside via electromagnetic fields

Uses other than illumination

A clear glass 60 W Neolux light bulb

Lamps can be used as heat sources, for example in incubators and toys such as the Easy-Bake Oven.

Filament lamps have long been used as fast acting thermistors in electronic circuits. The filaments are most likely made out of tungsten. Popular uses have included:

• Stabilisation of sine wave oscillators
• Protection of tweeters
• Automatic volume control in telephones

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.  Another Electronic symbol for Lamp

See also

• Electric light
• Light source
• Light tube
• List of light sources