Photoelectric effect measurements on a conventional neon bulb

Abstract

This work outlines a new instructional laboratory experiment focused on the photoelectric effect and the determination of Planck's constant. The described laboratory system employs contemporary experimental techniques, including real-time data acquisition based on the use of Arduino boards. The basis of this experiment is to measure the associated turn-on voltages of a small neon bulb as it is illuminated with several different optical wavelengths. Six different LED and laser illumination sources were used with wavelengths ranging from UV (383 nm) to red (659 nm). A plot of the bulb's turn-on voltage as a function of the inverse of the excitation wavelength showed a linear relationship with a high correlation coefficient. Planck's constant was determined from this plot, yielding a value of $h=\left(7.4\pm 1.1\right)\times {10}^{-34}\hspace{0.17em}\mathrm{J}·\mathrm{s}$ . Additionally, the system allows for experimental verification of the independence between excitation light intensity and the energy needed to ionize the gas inside the bulb.