PASCO SF-9405 RESONANCE WIRE LOOP - Manual

Instruction Sheet
for the PASCO
Model SF-9405
RESONANCE WIRE LOOP
012-04488B
1/91
$1.00
Introduction
The PASCO Wire Loop demonstrates standing waves on a
closed circular wire. It can also be used to show the phenom-
ena of de Broglie matter waves.
Theory
In 1913, Bohr formulated the well-known planetary model
of the atom. In this model, an electron orbiting farther from
the nucleus is in a higher energy state than one in a closer
orbit. Radiation of light from from the electron takes place
when the electron moves from a higher energy level to a
lower energy level. This model solved the mystery of atomic
spectra.
However, the fact that electrons may occupy only certain
energy levels confounded Bohr and other investigators. The
electron was considered to be a particle that could orbit
around its nucleus at any radial distance (depending on its
speed). But this doesn't happen. The mystery of discrete
energy levels can be understood by considering the electron
to be not a particle, but a matter wave.
Louis de Broglie presented the idea of matter waves in 1924.
He suggested that a wave was associated with every particle.
The wavelength of a matter wave is inversely proportional to
the particle's momentum. A Bohr orbit exists where an
electron matter wave reinforces itself constructively. In this
view, the electron is thought of as though its mass and
charge are spread out into a standing wave surrounding the
atomic nucleus. The wavelength of the matter wave must fit
evenly into the circumferences of the orbits. The innermost
orbit has a circumference of one electron wavelength, the
second orbit has a circumference of two electron wave-
lengths, and so on. For each orbit the electron has a unique
speed, and therefore a unique wavelength.
The PASCO Wire Loop will have standing waves at discrete
frequencies, each one corresponding to a unique wavelength.
Additional Equipment Required:
• Mechanical Driver, PASCO Model SF-9324
• Function Generator with Amplifier, PASCO Model
PI-9587A or PI-9598
• Support for holding the mechanical driver approxi-
mately 40 cm above the table top.
Setup Procedure
1. Loosen the screw on the banana plug which holds the two
ends of the loop. Adjust the banana plug perpendicular to the
plane of the loop as shown in the Equipment Setup figure.
Tighten the screw.
Equipment Setup