THERMODYNAMICS
Radiometer || Leslie's Cube || Stefan-Boltzmann Source || Special Thermodynamics Package
Radiometer
- Sturdy with a broad range of sensitivity
An instrument to measure the energy in a beam of radiation. Calibrated in Watts per meter², this apparatus will measure the energy of direct sunlight at the high end of its sensitivity down to the warm spot left by a human hand pressed on a wooden desk top. The detector is a thermopile consisting of a series of tiny thermocouples wired in series. The thermopile mounts in a substantial aluminum housing to maintain temperature stability. An integral shutter mounted in the housing cuts off the incoming radiation when adjusting the zero offset of the amplifier.
The detector has a flat spectral response from 0.3 µm in the ultraviolet to 15 µm wavelength in the infrared. The detector area of about 2 mm² is small enough to measure the energy in a laser beam. For broad sources of radiation, the instrument is sensitive through a 60° cone angle.
SPECIFICATIONS
Detector
A 14 junction thermopile
Spectral Range
0.3 µm to 15 µm
Sensitivity
1000 W/m² to 1 W/m² in 4 ranges
Controls
Range switch, zero adjust, detector shutter
Dimensions
12 H x 9.5 W x 22.5 D cm
(4.7 x 3.7 x 8.7 in)
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Leslie's Cube
- Varied thermal emittance
- Comes complete with thermometer.
Designed to investigate thermal radiation as a function of temperature and surface finish, this brass cube has sides finished black, white, polished and dull metal. The thermal emittance of the sides vary by a factor of twenty from the black to the polished metal. The top has a filler tube that holds a thermometer, which is included with the apparatus. Filling the cube with hot tap water provides plenty of radiation to measure with the TEL-EG45 Radiometer.
SPECIFICATIONS
Size
7.5 cm cube
Material
Brass
Sides
Matte black paint, matte white paint,
dull brass, polished brass
Thermometer
Alcohol 0° to 120° C
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Leslie's Cube can be used with the Radiometer TEL-EG45 to investigate thermal radiation as a function of temperature and surface finish.
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Stefan-Boltzmann Source
- Measure radiation as a function of temperature.
When used with the TEL-EG45 Radiometer, this tungsten lamp provides a radiation source that can measure the energy radiated as a function of temperature. This relation was first set down from theoretical considerations by Stefan and Boltzmann. From the current through the lamp and the voltage across it, students can establish the filament resistance. From the change in filament resistance with current, students can determine the temperature. The linearity of the TEL-EG45 Radiometer makes the measurement of thermal radiation from the filament persuasive. The energy varies over four decades so that the results are very convincing.
A low voltage power supply such as the TEL-GP4303D is also needed.
When used with the Radiometer TEL-EG45 the Stefan-Boltzmann Source lets one measure energy radiated as a function of temperature.
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SPECIAL THERMODYNAMICS PACKAGE
Save $ by purchasing the Radiometer TEL-EG45, Leslie's Cube TEL-EH10
and the Stefan-Boltzmann Source TEL-EH15 in the special Thermodynamics Package.
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