The Photoelectric Effect

Photoelectric Effect

When light shines on the surface of a metal, electrons can be ejected from the surface.

Photon Energy Equation

E = hv (E = energy of photon; h = Planck's constant; v = frequency).

Speed of Light Equation

c = λv (c = speed of light; λ = wavelength; v = frequency).

Photon Energy and Wavelength

The energy of a photon is inversely proportional to its wavelength (E = hc/λ).

Absorption/Emission of a Photon

When a photon is absorbed (E increases) or emitted (E decreases) by an atom or molecule, the energy of the species changes by an amount equal to the energy of the photon.

Binding Energy (Eb or Φ)

The energy needed to remove an electron from the atom; this is the minimum energy (work function) required to eject an electron from the metal surface.

Photoelectric Effect Energy Conservation

Ephoton = KEelectron + (Total energy of the photon equals the kinetic energy of the ejected electron plus the binding energy).

Threshold Frequency (v0)/Maximum wavelength

The minimum frequency or maximum wavelength of light that must be used to eject an electron; the minimum energy is equal to the binding energy (Φ = hv0 = hc/λmax).

Photoelectron Current

The rate of emission of the photoelectrons, which is directly proportional to the intensity (brightness) of the light.

Kinetic Energy of Photoelectron

If the minimum energy is met, the kinetic energy of the ejected electron is dependent only on the energy (frequency/wavelength) of the light u