Summary The Photoelectric Effect

,✓Electromagnetic spectrum
✓Wavelength and frequency
✓Photons
✓Visible light & UV rays



ROYGBIV
Longest Shortest

Lowest Highest

, Photoelectric effect
• DEF: the photoelectric effect is the process whereby electrons are emitted from
metal surface when light or EM radiation of a suitable frequency is incident on
the surface.
Basically→ emission of electrons from a metal surface

, QUANTUM THEORY: MAX PLANCK
• Energy emitted by light and other EM radiation is not continuous
• This energy can be divided into small minimum quantities/packets aka photons (quantum)
• The energy of each photon is directly proportional to the frequency of the radiation
E = hx
= hx c


h= planck’s constant = 6,63 x 10^-34
f= frequency (Hz)
c= speed of light = 3,0 x 10^8

, NOW: the photoelectric effect explained from above
• When light photon with energy (E=hf) strikes the surface of a metal- all the
energy of that photon is transferred to the electron
• This photon must have a minimum amount of energy to overcome the force of
attraction between the metal and the electron + remove the electron from the
surface (work function)
• The electrons that are removed = photoelectrons ☺

Definitions:
• Work function
• Frequency threshold