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:

$A$ light with an energy flux of $18 \,W \,cm^{-2}$ falls on a non-reflecting surface at normal incidence. If the surface has an area of $20 \,cm^2$, the average force exerted on the surface during a $30$ minute time span is . . . . . . $\left(c=3 \times 10^8 \,ms^{-1}\right)$.

$A$ lamp delivers a luminous flux of $100 \,W$ to an absorber of area $1 \,cm^2$. The force due to radiation pressure is

$A$ bulb of $800 \text{ W}$ electrical power has an efficiency of $3 \%$. It is kept at the centre of a sphere of diameter $20 \text{ cm}$. The force exerted on its surface by the electromagnetic $(EM)$ wave is . . . . . . .

If $2.5 \times 10^{-6} \ N$ 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 flux of light just before it falls on the surface is .................. $W/cm^{2}$. (Round off to the Nearest Integer) (Assume complete absorption and normal incidence conditions are there)

If the total energy transferred to a surface in time $t$ is $6.48 \times 10^5 \,J$, then the magnitude of the total momentum delivered to this surface for complete absorption will be: