Interference I (Again!) PREFLIGHT

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The following three questions refer to the material you were to read in preparation for the lesson. Questions one and three require you to write a three or four sentence response. Number two is a multiple choice question. Click in the appropriate circle.

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1.

Thin Film Reflection

Three film reflection

This physlet models the transmission of light through layers with different indices of refraction. From the material in the chapter, explain briefly the following observations:
a) Why is the wave coming in on the left, jumping around?
b) Why is the wave in the middle, bigger than the waves on both sides?
c) Why is the wave on the right leaving the system, NOT jumping around?






2.

The top of a soap bubble turns black for a few seconds before the soap bubble pops, while underneath appear "iridescent" colors. (See also the figure on page 914). The colors and the black band are best explained by:

A rainbow spectrum of white light, black is really ultraviolet.

A negative rainbow, with one color missing. Black is all colors missing.

A bending of the light as it goes through the curved soap bubble film. The black part is flat.

Diffraction of light, like the colors on a CD. The black part is smooth.


3.

A hummingbird's feathers are iridescent colors. It is conjectured that the feathers have a layer (or up to 8 layers) of platelets with an index of refraction of 1.85 to produce the ruby red color of a hummingbird's throat. If these layers alternate with air, what is the distance between these platelets needed to produce the red color? (More information can be found at: http://www.portalproductions.com/h/iridescent.htm).





honors extra


Why is it that when a lightwave goes into a material with a different refractive index (or equivalently, a different speed for light), the frequency stays constant, but the wavelength changes. Couldn't the wavelength stay the same and the frequency change? And if the wavelength changes, does the light change color inside a medium of different refractive index?





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