cathode
rays=أشعة الكاثود
ONLINE ETYMOLOGY
DICTIONARY
- cathode
(n.)
-
1834, from Gk. kathodos "a way down," from kata- "down"
(see cata-)
+ hodos "way" (see cede).
So called from the path the electric current was supposed to take.
Related: Cathodic. Cathode ray first attested 1880, but the
phenomenon known from 1859; cathode ray tube is from 1905.
- cata-
- word-forming element from Gk.
kata-, before vowels kat-, from kata "down from, down to."
Its principal sense is "down," but with occasional senses
of "against" or "wrongly." Also sometimes used
as an intensive or with a sense of completion of action. Very
active in ancient Greek, this prefix is found in English mostly in
words borrowed through Latin after c.1500.
WIKIPEDIA:
Cathode rays (also
called an
electron beam or
e-beam) are streams of
electrons
observed in
vacuum
tubes. If an evacuated glass tube is equipped with two
electrodes
and a
voltage is
applied, the glass opposite of the negative electrode is observed to
glow, due to electrons emitted from and travelling perpendicular to
the
cathode (the
electrode connected to the negative terminal of the voltage supply).