A critical look at the photoelectric effect experiment: a detailed guide for an undergraduate instructor

Ashwin Mohan

Department of Physics, Institute of Chemical Technology (ICT), Mumbai

In attempts to explain the photoelectric effect and its theoretical significance, an overview of the experiment using typical sketched current-voltage (I-V) characteristics of phototubes is what is provided in many popular textbooks and lectures that are available on the internet. Here, we shall see that experiments performed on commercially available photoelectric-effect setups used in many teaching laboratories across India show some obvious differences compared to the `textbook-like' results, and that the interpretation of actual experimental results is complicated by several parameters and physical scenarios that become important from a pedagogical point of view. We shall look at how some issues and caveats related to these experimental findings can be addressed and reasoned by considering the details of the experimental setup used. We shall also see how one can successfully model the general features of typical I-V curves obtained in a photoelectric-effect lab experiment using a fairly quantitative treatment at the undergraduate level.