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Stefan’s Law Experimental Setup

Determination of  Stefan’s constant.

Commercially available electric lamps are used in a laboratory experiment for the verification of Stefan’s law. Assuming that the emissivity  of tungsten filament remains constant and that all the filament power goes out as radiation, Stefan’s T4 law can be verified from a log‐log plot of radiated power P against temperature T of the filament.The experimental value of the slope of the graph of log P vs log T for all these lamps is found to be 5, which shows that the emissivity of the filament surface is proportional to the temperature of the filament.

A simplified laboratory experiment consists of :

  1. Stefan’s constant experiment setup :
    • Highly precision variable power supply.
    • Digital voltmeter and milliammeter.
    • Photosensor current indicator.
  2. Small Lamp with photosensor in an enclosure.