Oscillations
and Waves > Waves > Interference and
Diffraction
DCS#
3B55.32
SOUND
WAVE INTERFERENCE:
PHASE REVERSED SPEAKERS
APPARATUS
radio or function generator
202-09-E
amplifier
202-09-B
pair of Bose speakers
202-cart
dpdt
switch
214-01-E
DESCRIPTION
White noise from the radio is
amplified and sent to two speakers set close together and
facing each other. Flip the switch to reverse the phase
of one of the speakers and the sound volume drops dramatically
due to destructive interference. Increase the distance
between the speakers and the sound returns from higher to
lower frequencies as the waves are no longer completely out of
phase.
Use the function generator to do this at a single frequency.
NOTES
One speaker is connected directly
to the amplifier, the other is connected through a reversing
switch. The input to the amplifier is the FM radio tuned
between stations. The amplifier is set to mono.
