Electromagnetic Waves Question 2
Question 2 - 2024 (27 Jan Shift 1)
A plane electromagnetic wave propagating in $\mathrm{x}$-direction is described by
$\mathrm{E}_{\mathrm{y}}=\left(200 \mathrm{Vm}^{-1}\right) \sin \left[1.5 \times 10^{7} \mathrm{t}-0.05 \mathrm{x}\right]$;
The intensity of the wave is :
(Use $\epsilon_{0}=8.85 \times 10^{-12} \mathrm{C}^{2} \mathrm{~N}^{-1} \mathrm{~m}^{-2}$ )
(1) $35.4 \mathrm{Wm}^{-2}$
(2) $53.1 \mathrm{Wm}^{-2}$
(3) $26.6 \mathrm{Wm}^{-2}$
(4) $106.2 \mathrm{Wm}^{-2}$
Show Answer
Answer: (2)
Solution:
$\mathrm{I}=\frac{1}{2} \varepsilon_{0} \mathrm{E}_{0}^{2} \times \mathrm{c}$
$\mathrm{I}=\frac{1}{2} \times 8.85 \times 10^{-12} \times 4 \times 10^{4} \times 3 \times 10^{8}$
$\mathrm{I}=53.1 \mathrm{~W} / \mathrm{m}^{2}$
