A415 nm xenon laser puts out 6.00 w of power with a beam 6.40 mm in diameter. the beam is pointed directly at a pinhole which has a diameter of 1.70 mm. how many photons of light will travel through the pinhole per second? assume that the intensity of the light is equally distributed across the whole area of the beam.

Explanation:

The given data is as follows.

   wavelength () = 415 nm

                                        = ( 1 nm = m[/tex])

Relation between energy and wavelength is as follows.

            Energy (E) =

where, h = planck's constant =

            c = velocity of light =

Therefore, calculate the energy as follows.

             Energy (E) =

                               =  

                                = J

Hence, energy is equal to J

As the number of photons in laser beam of 6W = J

                                 = per second

It is given that, diameter of the pinhole = 1.70 mm

Diameter of the beam = 6.40 mm

The ratio of pinhole area to area of beam  is as follows.

                    =

                    =

                    = 0.0705

Hence, calculate the no. of photons of light travelling through pin hole per second  are as follows.

                   =

                    =

Therefore,  we can conclude that no. of photons of light travelling through pin hole per second are photons/s.