$A$ small object at rest absorbs a light pulse of power $20\,mW$ and duration $300\,ns$. Assuming the speed of light as $3 \times 10^8\,m/s$,the momentum of the object becomes equal to $.........\times 10^{-17}\,kg\,m/s$.

$50\, W/m^2$ energy density of sunlight is normally incident on the surface of a solar panel. Some part of incident energy $(25\%)$ is reflected from the surface and the rest is absorbed. The force exerted on $1\, m^2$ surface area will be close to $(c = 3 \times 10^8\, m/s)$.

$A$ radiation of energy $E$ falls on a perfectly reflecting surface. The momentum transferred to the surface is (let $c$ be the speed of light).

$A$ totally reflecting small plane mirror placed horizontally faces a parallel beam of light as shown in the figure. The mass of the mirror is $20 \, g$. Assume that there is no absorption in the lens and that $30 \%$ of the light emitted by the source goes through the lens. Find the power of the source needed to support the weight of the mirror in $MW$ (take $g = 10 \, m/s^2$ and $c = 3 \times 10^8 \, m/s$):-

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)

$A$ 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