Light of wavelength 500 nm is incident on a thin sheet of plastic film (n= 1.50) in air. What is the thinnest the sheet can be so that the reflected light from the surfaces undergoes constructive interference?

Question

Quizplus · Accepted Answer

For constructive interference in thin films, the condition is 2nt = mλ, where n is the refractive index, t is the thickness, m is an integer (for the thinnest film, m=1), and λ is the wavelength in the medium. The wavelength in the film is λ/n = 500 nm / 1.5 = 333 nm. Solving 2(1.5)t = 333 nm gives t = 83 nm.

Light of Wavelength 500 Nm Is Incident on a Thin