JEE MAIN - Physics (2021 - 17th March Morning Shift - No. 28)
If 2.5 $$\times$$ 10$$-$$6 N average force is exerted by a light wave on a non-reflecting surface of 30 cm2 area during 40 minutes of time span, the energy flux of light just before it falls on the surface is ___________ W/cm2. (Round off to the Nearest Integer)
(Assume complete absorption and normal incidence conditions are there)
(Assume complete absorption and normal incidence conditions are there)
답변
25
설명
Pressure = $${{Intensity} \over C}$$ (for absorbing surface)
I = P $$\times$$ C
I = $${{2.5 \times {{10}^{ - 6}}} \over {30c{m^2}}}$$ N $$\times$$ 3 $$\times$$ 108 m/s
I = 25 W/cm2
I = P $$\times$$ C
I = $${{2.5 \times {{10}^{ - 6}}} \over {30c{m^2}}}$$ N $$\times$$ 3 $$\times$$ 108 m/s
I = 25 W/cm2