Oscillations
and Waves > Instruments > Resonance in Solids
DCS#
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STANDING WAVES IN A
COFFEE MUG
APPARATUS
coffee
mug
105A
spoon
105A
DESCRIPTION
Tap the mug with a spoon at 45 degree intervals
around the rim to hear alternating higher and lower frequencies.
Tapping the mug excites circular standing
waves around the rim whose nodes are 90 degrees apart. If the mug
is tapped so that the handle is at an antinode, the resonant frequency
is lower than if the handle is at a node because of the greater vibrating
mass.
