Engineers from Brazil and the UK have set a new record of acoustic levitation, hanging in the air with the sound of an object the size of a Golf ball. Previously, so flew only a drop of a substance and then a small, but also not quite ordinary objects, such as wires and two-dimensional plane.
At this time, ultrasonic waves that the human ear can generally hear not, is suspended in the air 50-mm Styrofoam ball. And this was the first demonstration in which scientists have been forced to levitate the object size is greater than the length of the sound wave (14 mm, that is, 3.6 times more).
Your achievement Mark de Andrade (Marco Andrade) and Julio Adamovsky (Julio Adamowski) from the University of são Paulo, and Anna Bernasco (Anne Bernassau) from the University of Heriot-watt in Edinburgh said in an article published in the journal Applied Physics Letters.
Acoustic levitation of small objects at pressure nodes of the standing wave is quite widely known, however, the maximum size of particles that can be made to levitate thus is a quarter wave length — that is only four millimeters, ” explains de Andrade. In our article we show that the combination of ultrasonic emitters allows you to move a much larger object.
By the way, the lifting force is such that the sphere soars to a height of seven millimeters (i.e. at a distance equal to approximately half the length of the sound wave).
There are several ways to make an object float in the air due to the sound. In this case, the engineers constructed a tripod of ultrasonic emitters, which provides levitation of the sphere from foam. Between the ball and the transducers a standing wave, which pushes the sphere into the air. Previously in other works of physics caught levitating objects in the pressure nodes of the standing wave, but in this case, the approach is different.
As written by the developers of the new system, the angle of the emitters and their number can be changed. In addition, they showed that in theory can be made to float in the air and objects in other shapes, as well as the larger sphere, and to change the position of flying objects. In future work we want to create a new device that will allow you to manipulate large objects in the air, ” says de Andrade.
Earlier, other experts also showed that it is possible to force to levitate a flat object larger than the wavelength. But then they were able to get only a vertical pressure and were forced to chop their facilities on the needle, so they literally flew away. Group de Andrade came up with a scheme in which the object occupies a stable position by itself without additional tweaks (tripod provides both vertical and lateral pressure).
Acoustic levitation, according to physicists, will allow you to work with hot materials and liquids, for example, in the microgravity of space. As the orbit drops due to the surface tension forces take larger sizes than on Earth, new technology can be used for more than bulk samples.