$A$ bulb of $800 \text{ W}$ electrical power has an efficiency of $3 \%$. It is kept at the centre of a sphere of diameter $20 \text{ cm}$. The force exerted on its surface by the electromagnetic $(EM)$ wave is . . . . . . .

If electromagnetic waves of power $600 \ W$ are incident on a non-reflecting surface,then the total force acting on the surface is

Which of the following is an incorrect statement regarding a photon?

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 $c$.)

An impulse laser may be treated as a source of photons that are emitted during the time interval of the pulse,which is followed by a time interval when no photons are produced. Pulses are periodically repeated. $A$ laser beam of diameter $d = 10 \, \mu m$ is directed upward and is perpendicular to the thin foil surface which has a reflection coefficient $\rho = 0.50$ (see the sketch of the experiment). The reflection coefficient of the surface is the ratio of the reflected energy to the incident energy. $A$ pulse with duration of $0.13 \, ms$ has a total energy of $10 \, J$. What is the mass of the piece of foil that can be supported in the air solely by the light pressure of the laser beam? (Take $g = 10 \, m/s^2$)