Sodium-vapor lamp

Uncommon card · No. 115511

A sodium-vapor lamp is a gas-discharge lamp that uses sodium in an excited state to produce light at a characteristic wavelength near 589 nm. Two varieties of such lamps exist: low pressure and high pressure. Low-pressure sodium lamps are highly efficient electrical light sources, but their yellow-orange light restricts applications to outdoor lighting, such as street lamps, where they are widely used. High-pressure sodium lamps emit a broader spectrum of light than the low-pressure lamps, but they still have poorer color rendering than other types of lamps. Low-pressure sodium lamps give only monochromatic yellow-orange light, inhibiting color vision at night. Single ended self-starting lamps are insulated with a mica disc and contained in a borosilicate glass gas discharge tube (arc tube) with a metal cap. They include the sodium-vapor lamp that is the gas-discharge lamp used in street lighting. Low-pressure sodium lamps typically use a BY22d bayonet base, while High-pressure sodium lamps...

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