24.3. Uncertainty Principle http://www.ck12.org
FIGURE 24.9
Light coming through a single slit, treated
as a wave.Similarly, the uncertainty in the object’s momentum would be∆p=hλsince the momentum depends upon wave-
length.
The uncertainties would multiply if both measurements were attempted simultaneously. Thus,
∆x∆p≈h
Heisenberg’s more detailed calculation (which we will not do here) yielded the inequality
∆x∆p≥ 2 hπ
It is important to notice that the more precise one of the measurements, the less precise the other measurement. In
principle then, one can measure either the position or the momentum of an object to any degree of precision, but not
both. In fact: the more precise one measurement, the less precise the other measurement.
Quantum mechanics changed the view of the atom from the orderly arrangement of the planetary atom to what is
known today as an electron cloud model. The fact that an electron has wavelike characteristics means it is spread
out in space. Thus, the notion of an exact location for an electron is incompatible with its very nature. Heisenberg’s
uncertainty principle essentially ensures that there can be no well-defined planetary model of the atom.
At best, we can say that the location of an electron within an atom is probabilistic. The orbits we speak of today are
the average values of probable locations of the electron within the atom.
This video shows a demonstration and explanation of the effect:
MEDIA
Click image to the left for use the URL below.
URL: http://www.ck12.org/flx/render/embeddedobject/67082