What is the minimum thickness of a glycerin film (n = 1.47)on which light of wavelength 600 nm shines that results in constructive interference of the reflected light? Assume the film is surrounded front and back by air.

Question

Quizplus · Accepted Answer

For constructive interference to occur, the thickness of the film must be equal to an integer multiple of half the wavelength of the reflected light. In this case, the reflected light will have a wavelength of 600 nm in air and a shorter wavelength of 411 nm in the glycerin film (due to the higher refractive index of glycerin).

So,

(2t/λ) = m

Where t is the thickness of the glycerin film, λ is the wavelength of the reflected light in air, and m is an integer.

Rearranging this equation, we get:

t = mλ/2n

Where n is the refractive index of glycerin.

Plugging in the values, we get:

t = (1/2) * 600 nm / 1.47 = 204 nm / 2 = 102 nm

Therefore, the minimum thickness of the glycerin film for constructive interference is 102 nm.

The correct choice is B.

What Is the Minimum Thickness of a Glycerin Film (N