Question

Which of the following is not an important consideration for thin-film interference?

Select one:

a. Light beams traveling along paths of different lengths can develop a phase offset

b. Light beams traveling through media of different indexes of refraction can develop a phase offset

c. The thickness of the thin-film must be on the order of the wavelength of light

d. Reflection at an interface can cause a phase shift of pi/2

Answer 1

Interference pattern is generated because of phase difference developed in light Rays(beams) as they travels different lengths in different medium . The thickness of film is also relevant as for a thick film coherency of beam is lost producing a weak or no interference pattern.( So option A,B,C are all relevant) .

Option D). Would have been relevant if caused phase shift mentioned of pi instead of pi/2 .

Due to reflection from a medium of higher refractive index light beam experience a phase shift of pi (. 180Degrees) not pi/2(90 degrees).

Ans ) option D