Photoelectric Effect Calculator

Calculate kinetic energy of emitted electrons using KE = hf - phi (Einstein's photoelectric equation).

nm
eV

Max Kinetic Energy

2.6599 eV

Photon Energy4.9599 eV
Threshold Wavelength539.1 nm

Max Kinetic Energy vs Photon Wavelength

Voir la formule →

Formule

## Photoelectric Effect Einstein explained that light consists of photons, each carrying energy E = hf. When a photon hits a metal surface, it can eject an electron if its energy exceeds the work function. ### Formula **KE_max = hf - phi = (hc/lambda) - phi** where phi is the work function (minimum energy to free an electron). The threshold wavelength is **lambda_0 = hc/phi**.

Exemple Résolu

UV light at 250 nm hitting sodium (work function = 2.3 eV).

  1. 01E_photon = hc/lambda = (6.626e-34 * 3e8) / (250e-9)
  2. 02E_photon = 7.95e-19 J = 4.96 eV
  3. 03KE_max = E_photon - phi = 4.96 - 2.3
  4. 04KE_max = 2.66 eV
  5. 05Threshold: lambda_0 = hc/phi = 1240/2.3 = 539.1 nm