Kostenloser Photoelectric Effect Rechner
Berechnen Sie electron kinetic energy aus the photoelectric effect. Kostenloser KE = hf - phi Rechner.
Max Kinetic Energy
2.6599 eV
Max Kinetic Energy vs Photon Wavelength
Formel
## 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**.
Lösungsbeispiel
UV light at 250 nm hitting sodium (work function = 2.3 eV).
- 01E_photon = hc/lambda = (6.626e-34 * 3e8) / (250e-9)
- 02E_photon = 7.95e-19 J = 4.96 eV
- 03KE_max = E_photon - phi = 4.96 - 2.3
- 04KE_max = 2.66 eV
- 05Threshold: lambda_0 = hc/phi = 1240/2.3 = 539.1 nm
Häufig Gestellte Fragen
What is the work function?
The minimum energy needed to remove an electron from a metal surface. It varies by material: cesium ~2.1 eV, sodium ~2.3 eV, copper ~4.7 eV, platinum ~6.4 eV.
Why was the photoelectric effect important in physics?
It proved that light has particle properties (photons), a key insight in quantum mechanics. Einstein won the Nobel Prize in 1921 for this explanation.
What happens if photon energy is less than the work function?
No electrons are emitted, regardless of light intensity. Increasing intensity sends more photons but each one still has insufficient energy.
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