If 2.5 × 10^-6 N average force is exerted by a light wave on a non - reflecting surface of 30 cm^2 area during 40 minutes of time span, the energy…

If $\displaystyle 2.5 \times 10^{-6} \mathrm{~N}$ average force is exerted by a light wave on a non - reflecting surface of $\displaystyle 30 \mathrm{~cm}^2$ area during $\displaystyle 40$ minutes of time span, the energy flux of light just before it falls on the surface is \_\_\_\_ $\displaystyle \mathrm{W} / \mathrm{cm}^2$. (Round off to the Nearest Integer) (Assume complete absorption and normal incidence conditions are there)