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8. Electromagnetic waves — Physics STD 12 Science — Question

CBSE BoardEnglish MediumSTD 12 SciencePhysics8. Electromagnetic waves1 Mark
MCQ
Electric field in a plane electromagnetic wave is given by ${E}=50 \sin \left(500 {x}-10 \times 10^{10} {t}\right) \,{V} / {m}$ The velocity of electromagnetic wave in this medium is :

(Given ${C}=$ speed of light in vacuum)

  • A
    $\frac{3}{2} {C}$
  • B
    $C$
  • ✓
    $\frac{2}{3} C$
  • D
    $\frac{{C}}{2}$
✓

Answer

Correct option: C.
$\frac{2}{3} C$
c
${V}=\frac{\omega}{{K}}=\frac{10 \times 10^{10}}{500}=2 \times 10^{8}$

$V=\frac{2 {C}}{3}$

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