A simple proposal to measure the Planck’s constant h with a ESP32 development board

Planck’s constant h plays a fundamental role in the quantum theory. The numerical value of this universal constant can be experimentally obtained in a wide variety of physical phenomena. Determining the numerical value of h using LEDs and identifying the threshold voltage in which these devices emit light has become a favorite example of obtaining a rather precise value of h with a simple and cheap experimental setup. In this article, we propose a laboratory exercise with a fully automatized data acquisition framework based on a development ESP32 board. We used four LEDs of different colors, which were separately characterized by their wavelength. Each LED was fed, and the light intensity was measured. The threshold voltage was determined for each of the colors we considered, and then h was determined within fairly good deviation from the world average value. Moreover, using this world average value of h we determined the deviation of the wavelength of an ultraviolet LED from the manufacturers quoted value with remarkably good agreemen.