Question

A discharge lamp rated at 25 W (1 W = 1 J/s) emits yellow light of wavelength 580 nm. How many photons of yellow light does the lamp generate in 1.0 s?

Answer 1

Answer:

the number of photons of yellow light does the lamp generate in 1.0 s is 7 x $10^{19}$

Explanation:

given information:

power, P = 25 W

wavelength. λ - 580 nm = 5.80 x $10^{-7}$ m

time, t = 1 s

to calculate the number of photon(N), we use the following equation

N = λPt/hc

where

λ = wavelength (m)

P = power (W)

t = time interval (s)

h = Planck's constant (6.23 x $10^{-34}$ Js)

c = light's velocity (3 x $10^{8} m/s^{2}$)

So,

N = λPt/hc

   = (5.80 x $10^{-7}$)(25)(1)/(6.23 x $10^{-34}$)(3 x $10^{8} m/s^{2}$)

    = 7 x $10^{19}$