Question

Find no of photons emitted per second by a 40 watt source of monochromatic light of wavelength 6000 amstrong

Answer 1

Answer:

E = n h f    where h f is the energy of a single photon

E/t = (n / t) * h f = (n / t) * h * (c / y)    where y = wavelength

n / t = (E / t) * y / (h * c)      and E / t = power = 40 Watts

n / t = 40 J/s * 6 * 10E-7 m / ( 6.63 * 10^-34 J-s * 3 * 10^8 m/s)

n / t = 240 / 19.9 * 10^19 / s = 1.21 " 10^20 / s