Photoelectric Effect Apparatus
The simple version of the Photoelectric equipment was nothing more than a metal plate attached to a positively charge electroscope. When light was shined upon the plate, the electroscope discharged.
In order to make better measurements, a new apparatus was created. As light strikes the target (gold color) it might emit electrons which are called photoelectrons. If photoelectrons are emitted from the target they will strike the collector (black post) and pass through the ammeter, registering a current, and then on to the positive side of the battery. A higher current on the Ammeter indicates that more photoelectrons are being emitted from the target.
By adjusting the voltage and polarity of the battery, it is actually possible to make the collector push photoelectrons away from it. This gives us a way to measure the kinetic energy of the ejected electrons.