Light with an energy flux of $25 \times 10^4 \, W/m^2$ falls on a perfectly reflecting surface at normal incidence. If the surface area is $15 \, cm^2$,the average force exerted on the surface is:

$A$ 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.)

$A$ pulse of light of duration $100 \ ns$ is absorbed completely by a small object initially at rest. The power of the pulse is $30 \ mW$ and the speed of light is $3 \times 10^8 \ m/s$. The final momentum of the object is:

$A$ lamp delivers a luminous flux of $100 \,W$ to an absorber of area $1 \,cm^2$. The force due to radiation pressure is

$A$ bulb of power $660 \,W$ radiates uniformly in all directions. The pressure exerted by the radiation on the surface at a distance of $5 \,m$ is

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 $g = 10 \, m/s^2$)