The unit consists a test plate and a black plate, as a comparator, all the physical properties,dimensions, & temp. are equal, heat losses from the both plates are same except radiation losses. Input difference will be due to difference in emissivity. Input given through separate dimmer so temp. of both can be kept equal. Emissivity can determined over a wide range of temperatures. The unit is provided with antirust an attractive powder coating

Determination of Stefan Boltzmann, constant, consists of a hemisphere surrounded by hot water obtained from a water heating tank. Blackend disc is inserted at the center of hemisphere. Heat is transferred into the disc from the hemisphere by radiation & its temperature begins to rise & Stefan Boltzmann constant is determined.

Determination of heat transfer in radition or Stefan boltzmann. leak tight evacuated cylinder provided with heater at center, heat given by heater is transmitted to cylinder wall & wall temperature raise, which is kept steady by circulating water. If Stefan boltzmann constant is assumed to be known, then heat transfer can be shown proportional fourth power of temp. if heat transfer is known, Stefan boltzmann constant is determined Control panel with necessary measuring instruments.