A 75 W light source emits light of wavelength 600 nm. (a) Calculate the frequency of the emitted light.
(b) How many photons per second does the source emit?

Answer

A, B, C, D

Explanation

(a) `f = (C )/(lambda)`
(b) `:.` Number of photons emitted per second
`N_1 = (Power of source)/(Energy of one photo) = (P)/(hc/lambda)`
`N_1 = (Plambda)/(hc)`
=((75)(600xx10^(-9))/((6.63xx10^(-34))(3xx10^8))`
`~~ 2.3 xx10^20 photons/s.`