Standing Waves on the Rim of a Goblet
Standing waves can be set up around the rim of a glass bowl or goblet
by stroking the edge with a rosined bow, similar to the technique used
to excite Chladni figures. The nodes
and antinodes may be located by holding a thin strip of paper against the
rim; when it buzzes, an antinode has been located. For a classroom demonstration,
the paper is replaced by a series of pith balls hung against the edge.
Zahm notes that the smallest number of segments that may be excited on
the rim is four. Thus, when properly positioned, alternate balls would
be at rest at the nodes, and the rest, at the antinodes, would be in motion.
REFERENCE: J. A. Zahm, Sound and Music, second edition (A.C.
McClurg & Co., Chicago, 1900), pp 203-204
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