Unformatted text preview: s the denser film the
reflected ray is inverted, just like a pulse traveling down a slinky is
inverted when it reflects at the connection point with a heavier spring. The
transmitted ray is not inverted, which is also the situation with slinky and
spring. When the transmitted ray encounters the soap-air interface at the
inside of the bubble, again some of it is reflected back. This time,
however, the wave is not inverted (just as a pulse traveling on a heavy
spring is not inverted when it reflects at the connection point with a
slinky). The two reflected rays may or may not be in phase; it depends on
how thick the film is.
Since white light is comprised of many wavelengths, those that are nearly
in phase after reflecting off the bubble surfaces will be reinforced
(constructive interference). This is the color that will appear on the bubble.
The other wavelengths are out of phase (destructive interference) and
are, at least partially, cancelled out.
Since gravity causes the bubble to be thic...
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