1 A thin film of oil n14 is floating on a piece of crown gla

1. A thin film of oil (n=1.4) is floating on a piece of crown glass (n=1.55). We shine light from air (n=1) onto the film. The reflection of the light off the bottom surface of the film is

A.hard, with no shift

B.soft, with a shift of half a wavelength

C. hard, with a shift of half a wavelength

D. there is no reflection - all is transmitted

2. Referring to the setup in Question 1, the reflection of light off the top surface of the oil film is

hard, with a shift of half a wavelength

soft, with a shift of a quarter of a wavelength

hard, with no shift

there is no reflection - all light is transmitted

3.

Referring again to the setup in the Question 1, suppose we shine light of wavelength 550 nm onto the film. Remember that index of refraction of the oil is 1.4, while that of crown glass is 1.55.   What is the wavelength of that light when it\'s inside the film?

550 nm

275 nm

355 nm

393 nm

4. Referring to the setup in Question 1 again, what is the total wavelength shift between the beam reflected off the top of the oil film and the beam reflected off the bottom of the oil film?

no wavelength shift

half a wavelength shift

a quarter of a wavelength shift

one full wavelength shift

Solution

1.hard, with no shift

2.hard, with no shift

3.393 nm

4.half a wavelength shift