Stefan-Boltzmann constant with good accuracy. This experiment highlights the fundamental relationship between temperature and radiation for black bodies and serves as a practical demonstration of the Stefan-Boltzmann law. Stefans Constant apparatus has been designed to study the Stefans law of radiation. Continuously variable, over load & short circuit protected DC regulated power supply of 0 to 20V. Voltmeter & Current meter are mounted on the front panel to measure the voltage & current.