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AP EAMCET · PHYSICS · Electromagnetic Waves

Which one of the following is the property of a monochromatic, plane electromagnetic wave in free space?

  1. A Electric and magnetic fields have a phase difference of \(\frac{\pi}{2}\)
  2. B The energy contributions of both electric and magnetic fields are equal
  3. C The direction of propagations is in the direction of \(\mathbf{B} \times \mathbf{E}\)
  4. D The pressure exerted by the wave is the product of its speed and energy density
Verified Solution

Answer & Solution

Correct Answer

(B) The energy contributions of both electric and magnetic fields are equal

Step-by-step Solution

Detailed explanation

The average electric energy density of EM wave in free space, \(\mu_E=\frac{1}{2} \varepsilon_0 E^2\) \(=\frac{1}{2} \varepsilon_0\left[\frac{E_0}{\sqrt{2}}\right]^2\) \(=\frac{1}{4} \varepsilon_0 E_0^2...(i)\) Average magnetic energy density of EM wave in free space,…