Acoustic Levitation
By Derek Teel
For Physics 212x Spring 2017
Instructor: David Newman
By Derek Teel
For Physics 212x Spring 2017
Instructor: David Newman
Introduction :
As current
information suggests, sound travels in a wave
similar to that of a sine or cosine function.
Depending on the frequency the wave gets a longer
or shorter wavelength, and amplitude affects the
"loudness" of the sound. Sound behaves like ocean
waves, there is a constant flow of crests and
troughs. The crests represent high pressure while
the troughs are low pressure. But there is also
something 
called
the "node" in which the
pressure doesn't
change at
all. This is a critical component that
has allowed researchers to
discover how to
levitate small objects using
nothing but sound. Left you
will see a GIF in which there are two
opposing
waves when the crests of the yellow
wave align with the troughs of
the grey wave
the purple wave goes to zero and vice
versa.
bestanimations.com
When the crests of both align with each other the amplitude doubles. The nodes in which pressure changes do not occur are where objects get trapped. The pressure under the nodes are higher than the downward force of gravity and thus leaving a net upward force on the object trapped in the node.
This form of levitation has been found to be able to hold a Styrofoam ball the size of a golf ball which was about 3.6 times larger than the 14-mm wavelength used to levitate it (phys.org/news). This means that we aren't necessarily restricted by the size of the object and amplitude/wavelength as previously thought.
History
→ called
the "node" in which the
pressure doesn't
change at
all. This is a critical component that
has allowed researchers to
discover how to
levitate small objects using
nothing but sound. Left you
will see a GIF in which there are two
opposing
waves when the crests of the yellow
wave align with the troughs of
the grey wave
the purple wave goes to zero and vice
versa. bestanimations.com
When the crests of both align with each other the amplitude doubles. The nodes in which pressure changes do not occur are where objects get trapped. The pressure under the nodes are higher than the downward force of gravity and thus leaving a net upward force on the object trapped in the node.
This form of levitation has been found to be able to hold a Styrofoam ball the size of a golf ball which was about 3.6 times larger than the 14-mm wavelength used to levitate it (phys.org/news). This means that we aren't necessarily restricted by the size of the object and amplitude/wavelength as previously thought.