What is the force exerted on a surface having an area of $10\, cm^2$ due to the radiation of the Sun?

$A$ point source of light is placed at the centre of curvature of a hemispherical surface. The source emits a power of $24 \, W$. The radius of curvature of the hemisphere is $10 \, cm$ and the inner surface is completely reflecting. The force on the hemisphere due to the light falling on it is $.......... \times 10^{-8} \, N$.

Electromagnetic waves of energy flux $75 \times 10^4 \ W m^{-2}$ are incident normally on a surface of area $40 \ cm^2$. If the surface absorbs the flux completely,the total momentum delivered to the surface in one second is:

Light with an energy flux of $9 \ Wcm^{-2}$ falls on a non-reflecting surface at normal incidence. If the surface has an area of $20 \ cm^2$, the total momentum delivered for complete absorption in one hour is:

Sunlight falls normally on a surface of area $36 \, cm^{2}$ and exerts an average force of $7.2 \times 10^{-9} \, N$ within a time period of $20 \, minutes$. Considering a case of complete absorption,the energy flux of incident light is:

$A$ flashlight of intensity $9 \, W/cm^2$ illuminates a perfectly reflective surface of area $300 \, cm^2$. The average force exerted on the surface due to the incident light photons is