3B Scientific Radiation of Heat__Leslie's Cube - Manual (Page 2)

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• Take off the lid and fill the cube with water or
oil (not exceeding approx. 130° C).
• Insert a thermometer for monitoring the tem-
perature and the stirrer into the appropriate
apertures. Close the lid again.
• The liquid used to warm the cube from within
must be well stirred to achieve an even heat
distribution.
• Set up the thermopile approx. 3 to 5 cm away
from Leslie's cube.
• Connect the multimeter to the thermopile and
set the mode switch to the smallest DC current
range. (The current measuring range will produce
a larger needle deflection in the comparison to the
voltage measuring range).
• After setting up the experiment, wait for a few
minutes before taking readings.
Note:
Readings may be made incorrect due to the influ-
ence of body heat or other external influences.
• Do not touch the thermopile while taking read-
ings.
• Avoid direct sunlight and do not set up the
appa-ratus in the vicinity of a heater/radiator.
The black and white lacquered faces emit ap-
proximately equal amounts of infrared radiation.
The reason for this is that white and black only
appear as such within the visible light spectrum. If
only the emitted thermal radiation is observed,
which has longer wavelengths than visible light,
both the white and black faces appear as so-called
grey bodies; in other words, both radiate all wave-
lengths within this range with equal intensity. By
contrast, the thermal emission of the metallic faces
is much weaker.
Fig 1 Experimental set-up