SACE Stage 2 Physics — Light & Atoms 3.2

Photoelectric Effect

Light of wavelength λ shines on a metal cathode in an evacuated tube. Depending on the sign and size of the voltage V between the plates, electrons that escape the metal are either pulled across to the collector or turned back before they get there. The ammeter reads the resulting current. Vary the lamp, vary the voltage, change the cathode metal, and write down what you see.