Answer:
The force exerted on the cardboard by the light is [tex]1.2\times 10^{-11}\ N[/tex]
Explanation:
It is given that,
Area of the cardboard, [tex]A=2\ cm^2=0.0002\ m^2[/tex]
Intensity of absorbance, [tex]I=18\ W/m^2[/tex]
Radiation pressure in case of absorption is given by :
[tex]P=\dfrac{I}{c}[/tex]...........(1)
c is the speed of light
The relation between force and pressure is given by :
[tex]P=\dfrac{F}{A}[/tex].......(2)
From equation (1) and (2):
[tex]F=\dfrac{IA}{c}[/tex]
[tex]F=\dfrac{18\ W/m^2\times 0.0002\ m^2}{3\times 10^8\ m/s}[/tex]
[tex]F=1.2\times 10^{-11}\ N[/tex]
So, the force exerted on the cardboard by the light is [tex]1.2\times 10^{-11}\ N[/tex]. Hence, this is the required solution.
