Average force exerted on a non-reflecting surface at normal incidence is $2.4 \times 10^{-4} \,N$. If $360 \,W/cm^2$ is the light energy flux during a span of $1$ hour $30$ minutes,then the area of the surface is: (in $\,m^2$)

Radiations of intensity $0.5\,W/m^2$ are striking a metal plate. The pressure on the plate is

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

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:

$A$ parallel beam of monochromatic light of frequency $\nu$ is incident on a surface. The intensity of the beam is $I$ and the area of the surface is $A$. Find the force exerted by the light beam on the surface if it is perfectly reflecting and the light beam is incident at an angle of incidence $\theta$. (The speed of light is denoted as $c$.)

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