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⚛️ Physics  ·  Electromagnetic Waves  ·  NEET & JEE

If the electric field amplitude of an EM wave is E<sub>0</sub> = 100 V/m, what is the magnetic field amplitude?

Answer: B 0 = 3.33 × 10⁻⁷ T.

  • A B<sub>0</sub> = 3.33 × 10⁻⁷ T
  • B B<sub>0</sub> = 100 T
  • C B<sub>0</sub> = 3 × 10¹⁰ T
  • D B<sub>0</sub> = 100/c T

Correct answer: A. B<sub>0</sub> = 3.33 × 10⁻⁷ T

Explanation: B<sub>0</sub> = E<sub>0</sub>/c = 100/(3×10⁸) = 3.33×10⁻⁷ T. The magnetic field amplitude is much smaller than the electric field amplitude in SI units.

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.

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