Laser light with an intensity of 40,000 W/m² perpendicularly hits a black perfect absorber rectangular area of width W = 27 mm and height H = 35 mm.What is the force this laser exerts on the area?

Question

Quizplus · Accepted Answer

The force exerted by the laser on the absorber can be calculated using the formula $F = \frac{Power}{c}$, where $c$ is the speed of light ($3 \times 10^8 m/s$). Given that the laser light is perfectly absorbed, the intensity (Power/Area) is 40,000 W/m^2, and the area of the rectangle is $W \times H = 0.027 m \times 0.035 m = 9.45 \times 10^{-4} m^2$. The total power is $Power = Intensity \times Area = 40,000 \times 9.45 \times 10^{-4} = 37.8 W$. Thus, $F = \frac{37.8}{3 \times 10^8} = 1.26 \times 10^{-7} N$.

Laser Light with an Intensity of 40,000 W/m2 Perpendicularly Hits

Laser Light with an Intensity of 40,000 W/m² Perpendicularly Hits