The sun delivers $10^3 W/m^2$ of electromagnetic flux to the earth's surface.

the radiation force on a roof of dimensions 8m x 20m, will be:

$3.33 \times 10^{–5}N$ $5.33 \times 10^{–4}N$ $7.33 \times 10^{–3}N$ None of these

$5.33 \times 10^{–4}N$

$ F = PA = \frac{I}{c} A = \frac{10^3\times 160}{3\times 10^8} = 5.33\times 10^{-4}N$