Although the transmission of light, and electromagnetic radiation generally, is correctly described by wave (physical) optics, there are situations for which ray (geometric) optics gives a sufficiently good approximation. For each of the situations described in the following, determine whether ray optics may be used or wave optics must be used. Part (a) Green laser light of wavelength 530 nm is incident on a 26-cm diameter mirror. Ray None of these. WavePart (b) Red laser light of wavelength 722 nm is incident on a molecule of size 114 nm. Wave Ray None of these

a)  the geometric optics is adequate (Ray)

b) wave optics should be used for the second case

Explanation:

In general, the approximation of the geometric optics is adequate when the dimensions of the system are much greater than the wavelengths and the wave optics should be used for cases in which the size of the system is from the length of the wave.

Let's apply this to our case

a) in this case the size of the system is d = 26 cm=0.26 m and the wavelength is alm = 530 10⁺⁹ m

   in this case

                    d >>> λ

therefore the geometric optics is adequate (Ray)

b) in this case the system has a size of d = 114 10⁻⁹ m with a wavelength of λ= 722 nm

for this case d of the order of lam

therefore wave optics should be used for the second case