What is the photoelectric effect?

The ejection of electrons from a metal surface when light shines on it. The kinetic energy of the ejected electrons depends on the frequency of the light, not its intensity.

What is Einstein's photoelectric equation?

K_max = hf − φ, where K_max is the maximum kinetic energy of ejected electrons, hf is the photon energy, and φ is the work function (minimum energy to liberate an electron).

What is the threshold frequency?

f₀ = φ/h. Light below this frequency cannot eject electrons, no matter how intense. This was crucial evidence that light behaves as discrete photons, not just waves.

What is a work function?

The minimum energy needed to remove an electron from the surface of a particular metal. Cesium has φ ≈ 2.14 eV; platinum has φ ≈ 6.35 eV.

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NSW · HSCModule 7

Photoelectric effect calculator

Einstein's equation K_max = hf − φ. Pick a metal (or enter your own work function) and a wavelength of incident light.

Inputs

Metal presetWork function φ (eV)Incident wavelength λ (m)Visible: 400 to 700 nm

Result

Max kinetic energy K_max

1.185e-19J

K_max

0.7400eV

Photon energy hf

3.100eV

Threshold frequency f₀

5.706e+14Hz

Threshold wavelength λ₀

525.4nm

Photoelectrons emitted?

Yes

K_max = hf − φ. If hf < φ, no electrons are emitted no matter how intense the light.

How this calculator works

The calculator converts wavelength to photon energy (hf), subtracts the work function, and reports the maximum kinetic energy of ejected photoelectrons. It also computes the threshold frequency and wavelength, below which no electrons are emitted.

Common questions

What is the photoelectric effect?: The ejection of electrons from a metal surface when light shines on it. The kinetic energy of the ejected electrons depends on the frequency of the light, not its intensity.
What is Einstein's photoelectric equation?: K_max = hf − φ, where K_max is the maximum kinetic energy of ejected electrons, hf is the photon energy, and φ is the work function (minimum energy to liberate an electron).
What is the threshold frequency?: f₀ = φ/h. Light below this frequency cannot eject electrons, no matter how intense. This was crucial evidence that light behaves as discrete photons, not just waves.
What is a work function?: The minimum energy needed to remove an electron from the surface of a particular metal. Cesium has φ ≈ 2.14 eV; platinum has φ ≈ 6.35 eV.