Lightsource

A light source is an object or region that emits electromagnetic radiation, primarily in the visible spectrum, though it may also emit non-visible wavelengths such as infrared or ultraviolet. Light sources can be natural or artificial. They may produce light through thermal radiation, electronic transitions in atoms and molecules, or luminescence.

Natural light sources include the sun and stars, which emit light across a broad spectrum due to high-temperature processes in their interiors. Fire and bioluminescent organisms produce light through chemical reactions. In astronomy, distant stars and galaxies are observed as light sources that illuminate the cosmos.

Artificial light sources are designed to convert energy into visible light efficiently. Common types include incandescent lamps, which emit light primarily as heat; fluorescent lamps that convert some of the energy into visible light; light-emitting diodes (LEDs) that produce light by electroluminescence; high-intensity discharge lamps and metal-halide lamps; and organic LEDs (OLEDs) used in display technology. The choice of source affects efficiency, color rendering, and lifetime.

Key properties include luminous flux measured in lumens, luminous intensity in candelas, and illuminance in lux. Color temperature describes the color appearance. The color rendering index assesses how accurately colors appear under the light. Many sources emit infrared and ultraviolet radiation outside the visible range, which is often a consideration for safety and design.

In practice, light sources are selected to balance brightness, energy use, color quality, and environmental impact across applications such as residential lighting, street lighting, displays, and signaling.