E_{0} = \sqrt{\frac{2 \times 10^{12}}{310^{8} \times 8, 8510^{- 12}}} = 2, 7 \times 10^{7} W m^{- 2}

${E_0=\sqrt{\frac{2\times 10^{12}}{310^8 \times8,8510^{-12} }}=2,7 \times 10^7\, \mathrm{Wm^{-2}}}$