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.

$A$ light bulb of power $100 \ W$ is placed at the centre of a hollow sphere of radius $10 \ cm$. If $66\%$ of the energy is converted into light,then the pressure exerted by the light on the surface of the sphere will be (Assume the surface of the sphere to be perfectly absorbing).

$A$ beam of white light is incident normally on a plane surface absorbing $70\%$ of the light and reflecting the rest. If the incident beam carries $10\,W$ of power,find the force exerted by it on the surface :-

$A$ plate of mass $10 \text{ g}$ is in equilibrium in air due to the force exerted by a light beam on the plate. Calculate the power of the beam,if the plate is perfectly absorbing.

Light falls on a non-reflecting surface normally. If the average force exerted on a surface with area $15 \text{ cm}^2$ during a $20 \text{ minute}$ time interval is $10^{-6} \text{ N}$,then the energy flux (intensity) of light is (Velocity of light $= 3 \times 10^8 \text{ ms}^{-1}$)

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: