Sodium-vapor lamp
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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.
A high-pressure sodium-vapor lamp
A low-pressure sodium lamp running at full brightness
Two Honda Fits under low-pressure sodium lamps. Both appear black, even though the car on the left is bright red, while the car on the right is actually black.
Color rendering index
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A color rendering index (CRI) is a quantitative measure of the ability of a light source to reveal the colors of various objects faithfully in comparison with a natural or standard light source. Light sources with a high CRI are desirable in color-critical applications such as neonatal care and art restoration.
