Free · Physics models
Photoelectric Threshold and Photon Energy
Relate photon frequency, wavelength and energy to a supplied material photoelectric threshold.
- Formula & worked example
- Private in your browser
- No signup
Calculator inputs
Loading calculator…
How to use this calculator
- Enter the known values in the units shown. Results update as you type.
- Where results are editable, change one to solve backwards. Lock a value to hold it fixed.
- Use the worked example to check the method. Reset restores the starting fields.
Private by default
Inputs and results stay in this browser tab. Bookify does not upload or store the values you enter.
Formula and method
energy max = 1.2407003 eV; wavelength = 374.74057 nm; wavelength0 = 599.58492 nm; wave energy = 3.3085341 eV; wave energy0 = 2.0678338 eV.
Kmax = h(f−f₀); λ = c/f; photon energy = hf.
Worked example
Enter these known values and leave the other values blank.
- Frequency
- 800 THz
- Threshold frequency
- 500 THz
- Wavelength
- 374.74 nm
- Threshold wavelength
- 599.6 nm
- Wave energy
- 3.3085 eV
- Threshold energy
- 2.068 eV
- Maximum kinetic energy
- 1.2407 eV
Assumptions and limitations
- Relate photon frequency, wavelength and energy to a supplied material photoelectric threshold.
- The model retains the historical rounded Planck value 6.62607004×10⁻³⁴ J·s and exact c. It is an instructional approximation, not a current precision constants calculator.
- No emission is possible below threshold in this single-photon model. A negative computed kinetic energy is flagged as invalid rather than interpreted as an emitted electron.
- Inputs and inverse outputs share the displayed unit selectors. Clear a known field to solve for it, and lock quantities that must remain fixed. Singular inverses may have no finite result.
Common questions
Does light intensity change maximum energy?
In the single-photon model maximum energy depends on frequency and the work function, not intensity.
Where does threshold frequency come from?
It must be supplied from a material work function or measurement; this calculator does not select materials.
References
Relate photon frequency, wavelength and energy to a supplied material photoelectric threshold. The model retains the historical rounded Planck value 6.62607004×10⁻³⁴ J·s and exact c. It is an instructional approximation, not a current precision constants calculator. No emission is possible below threshold in this single-photon model. A negative computed kinetic energy is flagged as invalid rather than interpreted as an emitted electron.