Principle and Working:
According to stefan’s Boltzmann the energy emitted per unit area, per unit time of black body is directly proportional to the difference of 4th power of temperatures of hot body and surroundings. i.e. E = σ(T14- T24). Also when a temperature difference is maintained across the junctions of thermocouple, thermoelectric current is produced. It consists of a hollow metal hemisphere about 10 inches diameter with its inner surface blackened. This is placed inside a steam chamber. Steam can be passed through when desired, so that the temperature of the hemisphere becomes same as that of the steam. The temperature is measured with the help of the thermometers. The hemisphere rests on the wooden board provided with a small hole in the middle. The heat radiated by the black body is received by a small silver disc, blackened on its top. This disc can be inserted or taken out from the hole. One junction of a silver constantan thermocouple is soldered to the lower surface of disc, while the other is placed in water bath. A galvanometer is introduced in the thermocouple circuit. A shutter provided can be used to open or close the door.

Contents:

• Thermal and Electrical Conductivity of Metals
• Specific Heat of Solids
• Stefan Constant