Thermodynamics
> Heat and the First Law > Radiation
DCS#
4D20.10
RADIOMETER
APPARATUS
Crooke's radiometer
202-11-D2
gooseneck lamp
101-16-B
or hot plate
101-12-D
DESCRIPTION
The radiometer has four vanes that
are black
on one side and white or silver on the other. The vanes are
supported
in the center and free to pivot. Shine light or heat on the
radiometer.
The black faces will absorb more radiation, heat the adjacent air by
conduction,
and collisions with those faster moving air molecules cause the vanes
to turn.
NOTES
Place the radiometer near dry ice
and it will
run backward.
