$A$ $1.5 \,kW$ laser beam of wavelength $6400 \,\mathring A$ is used to levitate a thin aluminium disc of the same area as the cross-section of the beam. The laser light is reflected by the aluminium disc without any absorption. The mass of the foil is close to ......... $kg$.

An object is placed in a medium of refractive index $3$. An electromagnetic wave of intensity $6 \times 10^8 \ W/m^2$ falls normally on the object and it is absorbed completely. The radiation pressure on the object would be (speed of light in free space $= 3 \times 10^8 \ m/s$): (in $N/m^2$)

$A$ 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 $.........\times 10^{-17}\,kg\,m/s$.

$A$ laser beam with wavelength $\lambda = 633 \ nm$ has a power of $3 \ mW$. If the cross-sectional area of the beam is $3 \ mm^2$,what is the pressure exerted by the beam on a surface? (Assume the surface is a perfect reflector and the light is incident normally.)

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:

Given below are two statements: one is labelled as Assertion $(A)$ and the other is labelled as Reason $(R)$.
Assertion $(A)$: The electromagnetic wave exerts pressure on the surface on which they are allowed to fall.
Reason $(R)$: There is no mass associated with the electromagnetic waves.
In the light of the above statements,choose the correct answer from the options given below: