Photo Electric or PE effect is sometimes known as the  Planck's Constant apparatus. It is self contained and requires only 12V to run the light source. The inbuilt photo-tube is easily visible for inspection and the filters and apertures are stored in a special holder.

The housing has a sloping panel and large LCD display for measuring the tube current in 0.1 nanoamp increments. An excellent set of instruction sheets explains the various phenomena and guides the user through several important experiments.