Q127 / 180 · KCET 2023 · Physics

The ratio of the magnitudes of electric field to the magnetic field of an electromagnetic wave is of the order of

  • A
    $10^{-8} \mathrm{~ms}^{-1}$
  • B
    $10^5 \mathrm{~ms}^{-1}$
  • C
    $10^{-5} \mathrm{~ms}^{-1}$
  • Correct answer
    D
    $10^8 \mathrm{~ms}^{-1}$

Solution

As we known, $v=\frac{\mathbf{E}}{\mathbf{B}}$ or $v=\frac{|\mathbf{E}|}{|\mathbf{B}|}$ For an electromagnetic wave, $v=c$ $\therefore \frac{|\mathbf{E}|}{|\mathbf{B}|}=c=3 \times 10^8 \mathrm{~ms}^{-1}$ $\therefore|\mathbf{E}|:|\mathbf{B}|$ is of the order of $10^8 \mathrm{~ms}^{-1}$.

Hence, the correct answer is option: 'D'.

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