A glass tube that contains a metal plate (photocathode) and a smaller metal electrode (anode).Light of a frequency greater than the threshold frequency is directed at the photocathode.Electrons emitted are attracted to the anodeA microammeter measures the current.Photoelectric Current:
The current I is proportional to the intensity of the incident light.The intensity is proportional to the number of photons per second.The intensity does not affect the maximum kinetic energy. Each electron absorbs only one photonMaximum kinetic energy
Ekmax = hf - φ
Measuring Maximum Kinetic Energy:Using a photocell, different frequencies are plotted against EkmaxA straight line graph in the form y=mx+c is obtained.The gradient is h (Planck constant)