A glass envelope containing gas at low pressure, which gives light due to the collision of electrons with gas molecules. Discharge lamps, filled with one or more of various gases, are used to give colored light: mercury vapor gives purple, sodium vapor gives yellow, and neon gives red. Early discharge tubes, called Geissler tubes, were used as toys. A fluorescent lamp is a discharge tube coated internally with a fluorescent substance.
Related categories ATOMIC AND NUCLEAR PHYSICS
ELECTRICITY AND MAGNETISM
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