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8. Electromagnetic waves — Physics STD 12 Science — Question

CBSE BoardEnglish MediumSTD 12 SciencePhysics8. Electromagnetic waves1 Mark
MCQ
During the propagation of electromagnetic waves in a medium
  • A
    Electric energy density is half of the magnetic energy density
  • ✓
    Electric energy density is equal to the magnetic energy density
  • C
    Both electric and magnetic energy densities are zero
  • D
    Electric energy density is double of the magnetic energy density
✓

Answer

Correct option: B.
Electric energy density is equal to the magnetic energy density
b
$E_{0}=\mathrm{CB}_{0}$ and $C=\frac{1}{\sqrt{\mu_{0} \varepsilon_{0}}}$

Electric energy density $=\frac{1}{2} \varepsilon_{0} E_{0}^{2}=\mu_{E}$

Magnetic energy density $=\frac{1}{2} \frac{B o^{2}}{\mu_{0}}=\mu_{B}$

Thus, $\mu_{\mathrm{E}}=\mu_{B}$

Energy is equally divided between electric and magnetic field

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