A tank of gasoline (n = 1.40) is open to the air (n=1.00). A thin film of liquid

Question

A tank of gasoline (n = 1.40) is open to the air (n=1.00). A thin film of liquid floats on the gasoline and has a refractive index that is between 1.00 and 1.40. Light that has a wavelength of 625 nm (in vacuum) shines perpendicularly down through the air onto this film, and in this film the light looks bright due to constructive interference. The thickness of the film is 242 nm and is the minimum nonzero thickness for which constructive interference can occur. What is the refractive index of the film?

Explanation / Answer

constructive interference occurs when the optical thickness of the film is = wavelength/2

nd = lambda/2

n = 625/(2*242)

n = 1.29

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.