A 100 watt bulb emits monochromatic light of wavelength 400 nm. Calculate the number of photons emitted per second by the bulb.

Explanation

`E = nbv = n (hc)/(lamda) , 100 "watt" 100 J//s`, therefore,
`100 Js^(-1) = (n xx 6.6 xx 10^(-34) Js xx 3 xx 10^(8) ms^(-1))/(400 xx 10^(-9) m)`
`rArr n = 2 xx 10^(20) s^(-1)`