Q154 / 160 · AP EAMCET 2022 (08 Jul Shift 1) · Physics

If the amplitude of the magnetic field in a travelling plane electromagnetic wave is $2.2 \times 10^{-4} \mathrm{~T}$, then the intensity of the wave is nearly

  • Correct answer
    A
    $5.8 \times 106 \mathrm{Wm}^{-2}$
  • B
    $4.2 \times 106 \mathrm{Wm}^{-2}$
  • C
    $1.2 \times 107 \mathrm{Wm}^{-2}$
  • D
    $8.8 \times 105 \mathrm{Wm}^{-2}$

Solution

$I=\frac{B_0^2 C}{2 \mu_0}=\frac{\left(2.2 \times 10^{-4}\right)^2 \times 3 \times 10^8}{2 \times 4 \pi \times 10^{-7}}$ $=5.8 \times 10^6 \mathrm{Wm}^{-2}$

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

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