Maximum Kinetic Energy & Intensity (OCR AS Physics): Revision Note

The Maximum Kinetic Energy of Photoelectrons & Intensity

• The maximum kinetic energy of the photoelectrons is independent of the intensity of the incident radiation

• This is because each electron can only absorb one photon

• Kinetic energy is only dependent on the frequency of the incident radiation

• Intensity is a measure of the number of photons incident on the surface of the metal

• So, increasing the number of photons striking the metal will not increase the kinetic energy of the electrons, it will increase the number of photoelectrons emitted

Rate of Emission of Photoelectrons

• The photoelectric current is the rate of emission of photoelectrons emitted per second

• Photoelectric current is proportional to the intensity of the radiation incident on the surface of the metal

• This is because intensity is proportional to the number of photons striking the metal per second

• Since each photoelectron absorbs a single photon, the photoelectric current must be proportional to the intensity of the incident radiation

Kinetic energy of photoelectrons is independent of intensity, whereas the photoelectric current is proportional to intensity and independent of frequency