27.7 Thin Film Interference

Which of the following best describes the cause of thin film interference?

1. Light reflecting from a medium having an index of refraction less than that of the medium in which it is traveling.
2. Light reflecting from a medium having an index of refraction greater than that of the medium in which it is traveling.
3. Light changing its wavelength and speed after reflection.
4. Light reflecting from the top an…

A soap bubble is 100 nm thick and illuminated by white light incident perpendicular to its surface. What wavelength and color of visible light is most constructively reflected, assuming the same index of refraction as water?

Calculate the minimum thickness of an oil slick on water that appears blue when illuminated by white light perpendicular to its surface. Take the blue wavelength to be 470 nm and the index of refraction of oil to be 1.40.

A film of soapy water ($n = 1 . \text{33}$) on top of a plastic cutting board has a thickness of 233 nm. What color is most strongly reflected if it is illuminated perpendicular to its surface?

Suppose you have a lens system that is to be used primarily for 700-nm red light. What is the second thinnest coating of magnesium fluoride that would be non-reflective for this wavelength? Refer to the reference for the index of refraction.

A film of oil on water will appear dark when it is very thin, because the path length difference becomes small compared with the wavelength of light and there is a phase shift at the top surface. If it becomes dark when the path length difference is less than one-fourth the wavelength, what is the thickest the oil can be and appear dark at all visible wavelengths? Oil has an index of refraction of…

the figure shows two 7.50-cm-long glass slides illuminated by pure 589-nm wavelength light incident perpendicularly. The top slide touches the bottom slide at one end and rests on some debris at the other end, forming a wedge of air. How thick is the debris, if the dark bands are 1.00 mm apart?

Repeat the exercise, but take the light to be incident at a $\text{45}º$ angle.