What is the minimum thickness of a glycerin film (n = 1.47)on which light of wavelength 450 nm shines that results in constructive interference of the reflected light? Assume the film is surrounded front and back by air.
A) 150 nm
B) 76.5 nm
C) 204 nm
D) 102 nm

Question

Quizplus · Accepted Answer

The minimum thickness for constructive interference is given by: 
2t = (m + 1/2)λ/n 
where t is the thickness of the film, λ is the wavelength of light, n is the refractive index of the film, and m is an integer representing the order of interference. For m = 0 (first order), we get: 
2t = λ/ n 
Substituting the given values, we get: 
2t = 450 nm / 1.47 
t = 76.5 nm

What Is the Minimum Thickness of a Glycerin Film (N