The arc lamp was the first lamp
used, and was already
use by the late 1870s. Arc lamps have
a high intensity blueish white
light, and were used
s or to light
up large rooms, like factories.
The arc lamp
consists of two carbon
to a current limiter
and a power source
. When the
electrodes are pushed together and then slowly parted, an
arc will form through the ionize
d air between them.
This arc heats the electrodes to several thousand degrees.
s will glow with an intense light.
The problem with these lamps is that the electrodes must
constantly be readjusted, since the carbon vaporizes.
The first lamps had to be manually adjusted, but later
versions featured automatic adjustment and could even
restart the arc, if it was put out.