Question

A monochromatic red laser beam emitting 1 mW at a wavelength of 638 nm is incident on a silicon solar cell. Find the following: a. The number of photons per second incident on the cell b. The maximum possible efficiency of conversion of this laser c. beam to electricity

Answer 1

Step-by-step explanation:

First we calculate the energy of the photon

E=(Planck constant × speed of light in vacuum)÷ wave length

E=
`(6.626*10^(34)*2.998*10^(8) )/(638*10^(-9) ) = 3.114*10^(49)`

Next we find the total energy per second

total energy=
`1*10^(-3)W *(1JS^(-1) )/(1W) = 1*10^(-3) JS^(-1)`

Next we calculate the number the photon per second

= total energy ÷ energy of 1 photon

=
`(1*10^(-3) JS^(-1) )/(3.114*10^(49) ) = 3.21*10^(-53) \ photons/sec`