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Quantum Formula

What is Photon Energy?

The energy of a photon is inversely proportional to its wavelength — shorter wavelengths carry more energy.

Formula: E = \frac{hc}{\lambda}

Plain-English Meaning

The energy of a photon is inversely proportional to its wavelength — shorter wavelengths carry more energy.

When a quantum question feels ambiguous, translating it into state, observable, probability, and evolution language usually clarifies the answer.

Deeper Explanation

The energy of a photon is inversely proportional to its wavelength — shorter wavelengths carry more energy.

Worked Example

Problem: Find the energy of a photon of green light (λ = 520 nm).

  • E = hc/λ = (6.626×10⁻³⁴ × 3×10⁸) / (520×10⁻⁹)
  • E = 1.988×10⁻²⁵ / 5.2×10⁻⁷ = 3.82×10⁻¹⁹ J
  • E = 3.82×10⁻¹⁹ / 1.6×10⁻¹⁹ ≈ 2.39 eV

Result: E ≈ 2.39 eV

At A Glance

Category: Quantum

Levels covered:

Best use: Start with the formula meaning, then move to the worked example and quiz so the equation turns into a tool instead of a memorised line.