For patterns to be formed, the separation between the slits must be
comparable to the wavelength of the waves passing through them. Thus, as
your separation became very large, the pattern was not easy to see. While
wave behavior is exhibited by electrons, pions, neutrons and protons; we
do not observe similar behavior for large objects such as gnats or humans.
As an example, we will consider why diffraction doesn’t cause a gnat to
look like several gnats as it flies through window blinds. Suppose the
gnat’s mass is .001 kg, and its speed is 0.10 m/s.
? What is the gnat’s momentum?
? What is the gnat’s de Broglie wavelength? \
? Approximately what would the spacing between the window blinds have to be for the gnat to create a pattern as it flew through? Why?
? Is it necessary for a gnat to worry about creating a
pattern as it flies through the blinds? Why?
? How would a human being’s de Broglie wavelength
compare to that of a gnat? Why?
Because we know the values of Planck’s Constant and the electron’s mass,
we can use them to simplify the equation to apply only to electrons as:
? How does the relationship between energy and
wavelength in this formula compare with the relationship that you observed
in Activity 3?
A valid question to ask is: “What is waving with these matter waves?”
Unfortunately, the answer is not an easy one. We never observe a matter
wave directly; we only see results that can be explained by them. The
matter wave is an abstraction that allows us to explain observations. In
the next activity, we will look at what information is contained in waves
of matter. We will examine the features of matter waves that describe
simple properties such as the location of an object.
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