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A simple but accurate theory of how sound interacts with small particles has been developed by theoretical physicists at RIKEN. This advance will help to improve the manipulation of microparticles by sound.
Laser light is widely used to move and rotate small particles. This ability is grounded on knowledge of the forces and torques that light generates on small particles.
Way - Waves - Particles - Theory - Sound
In a similar way, sound waves can be used to manipulate small particles, but until now there was no clear and concise general theory that describes how non-uniform sound waves generate forces and torques on small particles.
Now, by considering analogies with light, Ivan Toftul, Konstantin Bliokh and Franco Nori of the RIKEN Theoretical Quantum Physics Laboratory and their co-workers have derived simple analytical expressions for the force and torque generated on a small spherical particle by a generic sound-wave field of a single frequency. These expressions reveal the direct link between the scattering force and the momentum density of the sound wave field and also that between torque and the wave field's spin angular momentum density.
Correspondences - Optics - Acoustics - Expression - Torque
"Such correspondences are now well established in optics, but it was rather vague in acoustics and there was no theoretical expression for the torque on...
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