# The average energy flux of sunlight is $1\: kW/m^2$. This energy is falling normally on the plate surface of area $10\: cm^2$ which completely absorbs the energy. How much force is exerted on the plate if it is exposed to sunlight for 20 minutes?
$\begin {array} {1 1} (a)\;33 \times 10^{-8}N & \quad (b)\;3.3 \times 10^{-8}N \\ (c)\;33 \times 10^{-9}N & \quad (d)\;3.3 \times 10^{-9}N \end {array}$