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

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.

$A$ light with an energy flux of $18 \,W \,cm^{-2}$ falls on a non-reflecting surface at normal incidence. If the surface has an area of $20 \,cm^2$, the average force exerted on the surface during a $30$ minute time span is . . . . . . $\left(c=3 \times 10^8 \,ms^{-1}\right)$.

If the radiant energy received from an electric bulb per second is $25 \ J/s$ and the velocity of electromagnetic waves is $c = 3 \times 10^8 \ m/s$,then the force exerted on the surface in one second is:

The force on a hemisphere of radius $1\, cm$ if a parallel beam of monochromatic light of wavelength $500\, nm$ falls on it with an intensity of $0.5\, W/cm^2$,striking the curved surface in a direction which is perpendicular to the flat face of the hemisphere is (assume the collisions to be perfectly inelastic).

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