The radiation pressure exerted by a $450 \ W$ light source on a perfectly reflecting surface placed at $2 \ m$ away from it is:

$A$ small mirror of mass $m$ is suspended by a massless thread of length $l$. Find the small angle through which the thread will be deflected when a short pulse of laser of energy $E$ falls normally on the mirror. ($c=$ speed of light in vacuum and $g=$ acceleration due to gravity)

$A$ 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.

If $P$ represents radiation pressure,$c$ represents the speed of light,and $Q$ represents radiation energy striking a unit area per second,then non-zero integers $x, y,$ and $z$ such that $P^x Q^y c^z$ is dimensionless are:

Light having an energy flux of $40 \ Wcm^{-2}$ 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) during $10 \ min$ is:

$A$ light beam of intensity $20 \,W/cm^2$ is incident normally on a perfectly reflecting surface of sides $25 \,cm \times 15 \,cm$. The momentum imparted to the surface by the light per second is