Calibrated in Watts/meter^2, the Radiometer will measure the energy of direct sunlight or the warm spot left by a human hand pressed on a wooden desktop. The thermopile detector consists 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 in the infrared. The detector area of about 2 mm^2 can measure the energy in a laser beam. For broad sources of radiation, the instrument is sensitive through a 60° cone angle.
Leslie's Cube demonstrates heat absorption and radiation. The cube features four sides with different finishes:
The top of the cube is fitted with a rubber stopper with a hole for the insertion of a thermometer (not included). When a lamp or other radiation source is shined onto the differing sides, students can investigate the varying properties of surface finishes by measuring the rate of heat absorption in the water inside. They may then measure the rate at which heat is released from the cube through a given side. The thermal difference between the sides may be as great as 20 times. The cube is 4 inches on each side.
When used with the Radiometer, the 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 physicists Stefan and Boltzmann. From the current through the lamp and the voltage across it, students can determine the temperature. The energy varies over four decades, so the results are very convincing.
- Demonstrate the Adiabatic Gas Law
- Compare work done on sample to change in internal energy
- Measure γ, the ratio of specific heats (Cp/Cv)
- Investigate isothermal processes
- Output to computer interface via 5-pin DIN connector
The Adiabatic Gas Law apparatus is the perfect tool for teaching confusing thermodynamic processes. The Adiabatic Gas Law apparatus simultaneously measures volume, pressure and temperature, completely specifying the state of the gas. The gas can be rapidly compressed or expanded, creating nearly adiabatic conditions. Alternately, processes can be performed slowly, creating isothermal conditions.
The TEL-TD45 Black Body Radiation Package includes the TEL-EG45 Radiometer, the TEL-612-1255 Leslie's Cube, and the TEL-EH15 Stefan-Boltzman Source. Using the TEL-EG45, students can measure black body radiation from sources with a wide range of temperatures. Leslie's Cube (TEL-612-1255) can be used as a source of black body radiation up to 120°C, while the different sides allow an investigation of emmissivity. The Stephan-Boltzmann Source can be used to investigate black body radiation from about 3000 to 3500 K.