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A plane sinusoidal linearly polarized electromagnetic wave of wavelength $5 \times 10^{-7}m$ travels in vacuum in the direction of $x$ - axis. The average intensity of the wave per unit area is $0.1\: W/m^2$ and the plane of vibration of electric field is parallel to $y$ - axis. The equations describing the electric and magnetic field of this wave is

$\begin {array} {1 1} (a)\; E_y = 2.9 \times 10^{-9} N/m \: \sin(4\pi \times 10^6) (t – x/c) & \quad (b)\;E_y = 8.67 N/m \: \sin(2 \pi \times 10^6) (t – x/c) \\ (c)\;E_y = 8.67 N/m \: \sin(4\pi \times 10^6) (t – x/c) & \quad (d)\;E_y = 2.9 N/m \: \sin(2 \pi \times 10^6) (t – x/c) \end {array}$

$E_o = \sqrt{\large\frac{2I}{\in_oc}}$
$=\sqrt{\bigg[ \large\frac{2 \times 0.1}{( 8.85 \times 10^{-12} \times 3 \times 10^8)} \bigg]}$$= 8.67$
$E_y = E_o \sin \bigg[\large\frac{2\pi (ct – x)}{ \lambda} \bigg]$
Ans : (c)