A photocell circuit can be used to study the flow of photoelectric current.
As shown in Diagram above, a photocell consists of a cathode (coated with light-sensitive material such as cesium or lithium) and an anode enclosed in a vacuumed glass tube.
When light falls on the cathode, photoelectrons are emitted due to the photoelectric effect.
Photoelectrons are attracted to the anode, causing a photoelectric current to flow in the circuit.
When the intensity of light increases, more photoelectrons are emitted from the cathode and the photoelectric current increases.
No photoelectric current is detected if the photoelectric effect does not take place (that is when frequency, \(f\) of incident photon < threshold frequency, \(\int_0\) of the metal surface).