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Chapter 6 — Chapter 6 — Quantum Physics
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📘Easy summary
Quantum theory assumes the behaviour of electromagnetic radiations as discrete packets of energy and particles on a very small scale to behave as waves. In 1901 Max Planck suggested that energy is radiated or absorbed in discrete packets of energy called quanta rather than as a continuous wave. Energy of each quantum (photon) E = hf = hc/λ, where h = 6.63 × 10⁻³⁴ J s is Planck's constant. As matter consists of tiny particles, so is radiation energy from a source. Planck received the Nobel Prize in 1918.
⭐Key points
- E = hf = hc/λ.
- h = 6.63 × 10⁻³⁴ J s.
- Higher f ⇒ more energetic photon.
🔬Diagram
🌿Real-life example
Photon of 350 nm: E = 6.63 × 10⁻³⁴ × 3 × 10⁸/350 × 10⁻⁹ = 5.68 × 10⁻¹⁹ J = 3.55 eV.
💡Exam tip
- Convert J to eV by dividing by 1.6 × 10⁻¹⁹.
✅Quick check
1. Energy of a photon is proportional to its:
2. Dimensions of h equal those of:
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