$A$ plate of mass $10 \text{ g}$ is in equilibrium in air due to the force exerted by a light beam on the plate. Calculate the power of the beam,if the plate is perfectly absorbing.

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

$A$ photon of wavelength $6630 \ \mathring{A}$ is incident on a totally reflecting surface. The momentum delivered by the photon is equal to

$A$ 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 $.......... \times 10^{-8} \, N$.

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:

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