$A$ plane electromagnetic wave travelling along the $X$-direction has a wavelength of $3 \ mm$. The variation in the electric field occurs in the $Y$-direction with an amplitude of $66 \ Vm^{-1}$. The equations for the electric and magnetic fields as a function of $x$ and $t$ are respectively:

• A
  $E_y = 33 \cos \pi \times 10^{11} (t - x/c), B_z = 1.1 \times 10^{-7} \cos \pi \times 10^{11} (t - x/c)$
• B
  $E_y = 11 \cos 2\pi \times 10^{11} (t - x/c), B_z = 11 \times 10^{-7} \cos 2\pi \times 10^{11} (t - x/c)$
• C
  $E_y = 33 \cos \pi \times 10^{11} (t - x/c), B_z = 11 \times 10^{-7} \cos \pi \times 10^{11} (t - x/c)$
• D
  $E_y = 66 \cos 2\pi \times 10^{11} (t - x/c), B_z = 2.2 \times 10^{-7} \cos 2\pi \times 10^{11} (t - x/c)$