Q151 / 160 · AP EAMCET 2022 (08 Jul Shift 1) · Physics

In a plane electromagnetic wave, the maximum value of the electric field component is $4.4 \mathrm{Vm}^{-1}$. The intensity of the wave is nearly

  • A
    $22.4 \mathrm{~mW} \mathrm{~m}^{-2}$
  • Correct answer
    B
    $25.7 \mathrm{~mW} \mathrm{~m}^{-2}$
  • C
    $65.5 \mathrm{~mW} \mathrm{~m}^{-2}$
  • D
    $45.6 \mathrm{~mW} \mathrm{~m}^{-2}$

Solution

We know that $\mathrm{I}=\frac{1}{2} \varepsilon_0 \mathrm{E}_0^2 \mathrm{C}$ $\begin{aligned} & =\frac{1}{2} \times 8.85 \times 10^{-12} \times 4.4^2 \times 3 \times 10^8 \\ & =25.7 \mathrm{~mW} / \mathrm{m}^2\end{aligned}$

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

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