An electromagnetic wave of intensity $1400 \, W/m^2$ falls on a metal surface of area $1.5 \, m^2$ and is completely absorbed by it. Find the force exerted by the beam.

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 $N/m^2$)

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

$A$ $1.5 \,kW$ 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 ......... $kg$.

Radiation of intensity $I$ is falling obliquely on a surface. The area of the surface exposed to radiation is $A$. The angle of incidence with the normal is $\theta$. Select the correct alternative,where $\beta$ is a constant that depends upon the nature of the surface.

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: