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⚛️ Physics  ·  Electromagnetic Waves  ·  NEET & JEE

The photon energy of a UV photon (λ = 200 nm) is:

Answer: 6.2 eV.

  • A 6.2 eV
  • B 12.4 eV
  • C 1.24 eV
  • D 62 eV

Correct answer: A. 6.2 eV

Explanation: E = hc/λ = (4.136×10⁻¹⁵ eV·s × 3×10⁸ m/s)/(200×10⁻⁹ m) = 1.24×10⁻⁶/200×10⁻⁹ = 6.2 eV. UV photons have enough energy to break chemical bonds (≥ 3.5 eV).

Electromagnetic Wave: E ⊥ B ⊥ Direction of TravelpropagationE (electric field, vertical plane)B (magnetic field, horizontal plane, perpendicular to E)

In an electromagnetic wave, the oscillating electric field (E) and magnetic field (B) are perpendicular to each other and to the direction the wave travels - a purely transverse wave that needs no medium, unlike sound.

Concept context

Maxwell's equations, EM spectrum, properties, and applications of each band.

Read the full Electromagnetic Waves notes →