Monochromatic light of wavelength $\lambda$_film is normally incident on a soap film in air. In terms of the wavelength, what is the thickness of the thinnest film for which the intensity of the reflected light will be a maximum? A)$\lambda$_film/4 B)$\lambda$_film/2 C)3 $\lambda$_film/4 D)$\lambda$_film E)3 $\lambda$_film/2

Question

Quizplus · Accepted Answer

For constructive interference in a thin film, the optical path difference should be an integer multiple of the wavelength. For the thinnest film, the thickness is $\lambda$_film/4, considering a phase shift upon reflection.

Monochromatic Light of Wavelength λ\lambdaλ film Is Normally Incident on a Soap Film in Air

Monochromatic Light of Wavelength $\lambda$ _film Is Normally Incident on a Soap Film in Air