He-Ne Laser device emits photons of wave length 632.8 nm by rate 4.5 x 1020 photon/s, so the power of the laser beam =
a. 3.14 W
b. 141.3 W
c. 314.1 w
d. 431.4 W​

Option b.

Explanation:

We know:

Wavelength = 632.8 nm

Fluence = 4.5*10^20 photon/s

The energy of a single photon of wavelength λ is:

E = (h*c)/λ

where:

h = 6.6*10^(-34) J*s

c = 3*10^8 m/s

And we should rewrite the wave length in meters, so:

λ = 632.8 nm = 632.8*10^(-9) m

replacing these in the energy equation, we get:

E = (6.6*10^(-34)J*s)*(3*10^8 m/s)/(632.8*10^(-9) m) = 3.13*10^(-19) J

So each one of the  4.5x10^20 photon that flow each second have this energy, then the power is:

P = (3.13*10^(-19) J)*(4.5*10^20 /s) = 140.85 J/s

and 1 W = 140.85 J/S

Then the power is:

P = 140.85 W

Then the correct answer is the option b, where the units are a little bit different than mine because I used really simplified values for c and h.

energy can be converted from one form to another, but it cannot be created or destroyed in ordinary chemical or physical means. do not understand what you are asking but hope this