This apparatus has a photo-tube with a nano-ammeter to measure the photo-current created by the photoelectric effect. A backing voltage can be applied to measure the stopping voltage. The apparatus possesses 5 different coloured LED’s so that the stopping voltage for known frequencies can be determined. From this the work function, threshold frequency and Planck’s constant can be calculated.
NSW Physics Syllabus Reference
Module 7: The Nature of Light
Light Quantum Model
- Analyse the photoelectric effect 𝐾max = ℎ𝑓 − 𝜙 as it occurs in metallic elements by applying the law of conservation of energy and the photon model of light