Light Waves, Color, and Soap Bubbles

[beefcakes_mcg]

Homework Statement

A soap bubble is floating in the air. The wall of the bubble
has an index of refraction of n = 1.33. It is observed that red and
violet light are reflected from the surface of the bubble, but no
green light is reflected. Compute the minimum thickness of the
bubble.

Homework Equations

v=fλ
c=3x10^8

The Attempt at a Solution

I'm pretty much just confused on where to start. I'm assuming it has something to do with the color destructively interfering with the soap bubbles, so that only some of the color reflects. Do I start by picking the smallest possible wavelength that includes both red and blue cones, and then assume that the speed of light is slower due to the soap material, THEN assume that the soap bubble has to be one wavelength long?

 

[ehild]

I'm pretty much just confused on where to start. I'm assuming it has something to do with the color destructively interfering with the soap bubbles, so that only some of the color reflects. Do I start by picking the smallest possible wavelength that includes both red and blue cones, and then assume that the speed of light is slower due to the soap material, THEN assume that the soap bubble has to be one wavelength long?

There is interference between the waves reflected from the front surface and the back surface of the wall of the bubble. The interference is destructive for green light.


ehild