home
***
CD-ROM
|
disk
|
FTP
|
other
***
search
/
The Epic Interactive Encyclopedia 1998
/
Epic Interactive Encyclopedia, The - 1998 Edition (1998)(Epic Marketing).iso
/
D
/
Discharge_tube
/
INFOTEXT
< prev
Wrap
Text File
|
1992-09-02
|
693b
|
17 lines
Device in which a gas conducting an electric
current emits visible light. It is usually a
glass tube from which virtually all the air
has been removed (so that it `contains' a
near vacuum), with electrodes at each end.
When a high-voltage current is passed between
the electrodes, the few remaining gas atoms
in the tube (or some deliberately introduced
ones) ionize and emit coloured light as they
conduct the current along the tube. The light
originates as electrons change energy levels
in the ionized atoms. By coating the inside
of the tube with a phosphor, invisible
emitted radiation (such as ultraviolet light)
can produce visible light; this is the
principle of the fluorescent lamp.