Set the demonstration up as shown.  The filters will show at which spectral wavelengths the photocell works best. The photocell shown and the others that are available do not work exactly like the classical cells described in most of the text books because they are made of other alloys than those in the texts. Therefore the filters used for maximum effect are also in a different region of the spectrum and also have a broader bandwidth.

Another simple way to show that the shorter wavelengths contain most of the energy is to use different color LED's with some fluorescent material.  The material will not be activated with the red, orange, yellow, and green lights.  The blue and white lights will give some activation, but are nothing compared to the activation provided by the ultraviolet light.   

The Cenco units will also show the photoelectric effect using different colored filters and an incandescent light.  These are intended as a lab experiment and therefore not as large and visual as the setup described in the first paragraph.