Question

If solar radiation is 1200 w/m2 , how many photons strike the leaf every second? Assume three significant figures and an average wavelength of 504 nm for solar radiation.

Answer 1

Power received by the beam of photons is given as

Power = number of photons per second * energy due to one photon

$P = N*\frac{hc}{\lambda}$

here we know that

$h = 6.6 * 10^{-34}$ = planck's constant

$c = 3 * 10^8 m/s$ = speed of light

$\lambda = 504 nm$ = wavelength of photons

$P = N*\frac{6.6 * 10^{-34} * 3 * 10^8}{504 * 10^{-9}}$

$1200 = N * 3.92 * 10^{-19}$

$N = 3.05 * 10^{21}$

so above photons per second strike with it