Photoelectric Effect Calculator

Summary

This calculator applies Einstein's photoelectric equation KE_max = hf − φ to find the maximum kinetic energy of electrons ejected from a metal surface. Enter a photon wavelength or frequency and select a metal (or provide a custom work function). The tool reports photon energy in eV and joules, whether emission occurs, maximum kinetic energy, threshold frequency and wavelength, stopping voltage, and maximum electron speed.

How it works

1. Enter the photon wavelength (nm) or switch to frequency (Hz) mode.
2. Select a metal from the dropdown or type a custom work function in eV.
3. The calculator converts wavelength to photon energy using E = hc/λ.
4. Max kinetic energy is found from KE_max = E_photon − φ (work function).
5. Threshold frequency f₀ = φ/h and threshold wavelength λ₀ = hc/φ are derived from the work function alone.
6. Stopping voltage V₀ = KE_max / e and max electron speed v = √(2·KE/m_e) are computed when emission occurs.

Use cases

• Solve photoelectric effect problems in introductory quantum mechanics courses.
• Verify which metals emit electrons under UV, visible, or near-IR illumination.
• Compute the stopping voltage needed to halt emitted electrons in a phototube.
• Find the threshold wavelength for a given photocathode material.
• Explore how changing photon frequency above the threshold affects electron kinetic energy.
• Cross-check lab measurements of photocurrent cut-off with theoretical values.

Frequently Asked Questions