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⚛️ Physics  ·  Electromagnetic Waves  ·  NEET & JEE

EM waves carry linear momentum. The momentum of a photon of frequency f is:

Answer: p = hf/c = h/λ.

  • A p = hf/c = h/λ
  • B p = hf
  • C p = hf²/c
  • D p = hc/f

Correct answer: A. p = hf/c = h/λ

Explanation: Photon momentum p = E/c = hf/c = h/λ. This momentum causes radiation pressure and is used in laser cooling of atoms and solar sail propulsion concepts.

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 →