The Photoelectric Effect: Basics (Cambridge International A-Level Physics)

The photoelectric effect: basics

The photoelectric effect

• The photoelectric effect is the phenomenon in which electrons are emitted from the surface of a metal upon the absorption of electromagnetic radiation

• Electrons removed from a metal in this manner are known as photoelectrons

• The emission of photoelectrons is known as photoelectric emission

• The photoelectric effect provides important evidence that light is quantised

  • Each photon has energy hf, and each electron can absorb only a single photon
  • An electron is emitted only if hf is at least the work function $Φ$, so there is a minimum (threshold) frequency $f_{0}=\frac{Φ}{h}$, whatever the intensity

The photoelectric effect

Photoelectrons are emitted from the surface of metal when light shines onto it

Exam Hint Make sure to brush up on common misconceptions:

• The electrons are already in the metal, they are not produced in any way by the incoming light rays
• Each electron can absorb only one photon