Question

Monochromatic light has frequency 10 ^15hz and surface area 2 cmsquare. If the intensity of the light is 30×10^-2 W/m square. Determine the rate at which photons strikes at surafce

Answer 1

Answer:

Let the number of photons striking the surface per second (rate) = n

Energy of each photon, E = hυ = 6.626 x 10⁻³⁴Js x 10¹⁵ Hz = 6.626 x 10⁻¹⁹J

Power imparted, P = nE

Intenisty, I = P/Area = nE/Area

n = IA/E = 0.3 x 2 x 10⁻⁴/ 6.626 x 10⁻¹⁹J = 9.06 x 10¹³

∴ n = 9.06 x 10¹³ photons per second