The equation for photon energy, e, is e=hcλ where h = 6.626×10−34 j⋅s (planck's constant) and c = 2.99×108 m/s (the speed of light). what is the wavelength, λ, of a photon that has an energy of e = 3.65×10−19 j ?

Energy of a photon = hc/λ
           3.65 x 10^-19 = 6.626 x 10^-34 x 2.99 x 10^8/λ
                                λ = 6.626 x 10^-34 x 2.99 x 10^8 / 3.65 x 10^ -19
                                   = 5.42 x 10^-7 m.

Hence wavelength of photon is 5.42 x 10^-7 m.

Hope this helps, have a great day/night ahead!

                              

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It shows that the experiment is designed properly.