4/30/2023 0 Comments Are soundwaves transverse![]() ![]() volumetric air confined in small resonators with size much smaller than the wavelength. Then he conceived the idea that synthetic shear force may arise if the air is discretised into “meta-atoms”, i.e. He had been exploring if it is possible to realise transverse sound, which requires shear force. The absence of shear force in the air, or fluids, is the reason why sound is a longitudinal wave, Dr Wang explained. Illustration of the “meta-atom” and transverse sound.Ĭredit: Wang, S., Zhang, G., Wang, X. et al. / DOI number: 10.1038/s41465-9 The finding provides new degrees of freedom for sound manipulations.” the coupling between two types of angular momentum. And we investigated its spin-orbit interactions (an important property only exists in transverse waves), i.e. “ While the airborne sound is a longitudinal wave in usual cases, we demonstrated for the first time that it can be a transverse wave under certain conditions. “If you speak to a physicist about airborne transverse sound, he/she would think you are a layman without training in university physics because textbooks say that airborne sound (i.e., sound propagating in the air) is a longitudinal wave,” said Dr Wang. But the latest discovery by scientists from CityU changes this understanding of sound waves. In longitudinal waves like sound, the vibrations are parallel to the direction of wave propagation. In transverse waves like light, the vibrations are perpendicular to the direction of wave propagation. The physics textbooks tell us there are two kinds of waves. It was published in Nature Communications, titled “ Spin-orbit interactions of transverse sound”.īeyond the conventional understanding of sound wave The research was initiated and co-led by Dr Wang Shubo, Assistant Professor in the Department of Physics at CityU, and conducted in collaboration with scientists from Hong Kong Baptist University (HKBU) and the Hong Kong University of Science and Technology (HKUST). The findings shattered scientists’ previous beliefs about the sound wave, opening an avenue to the development of novel applications in acoustic communications, acoustic sensing and imaging. Transverse mechanical waves can only move through solid materials, longitudinal waves can move through solids, liquids, and gases.Can you imagine sound travels in the same way as light does? A research team at City University of Hong Kong (CityU) discovered a new type of sound wave: the airborne sound wave vibrates transversely and carries both spin and orbital angular momentum like light does. The wave energy is transferred horizontally to the right. In the longitudinal wave above, the leftmost particle is vibrated horizontally in simple harmonic motion, causing the particles to its right to also vibrate in simple harmonic motion. Longitudinal Wave - A wave in which the particles of the medium move parallel to the direction of the wave motion. This type of a wave is called a Longitudinal Wave. Waves can also move through a material when the particles of the medium vibrate back and forth in the direction the wave is moving. Transverse Wave - A wave in which the particles of the medium move perpendicular to the direction of the wave motion. This specific type of wave motion is called a Transverse Wave. Note that the particles are vibrating up and down (in the vertical direction), while the wave itself is transferred from left to right (horizontally). This oscillation is passed down through the entire series of particles. In the diagram above, the motion of the particle farthest to the left causes the particle next to it to oscillate. If this particle is bonded to other particles near it, its motion will affect the motion of the particles around it. Imagine that this ball represents a particle in a solid material. The blue ball above is in simple harmonic motion. When a mechanical wave moves through a physical medium, the particles in the medium oscillate in simple harmonic motion. Examples: Radio waves, visible light, x-rays, etc. Electromagnetic waves can travel through a vacuum. Sound waves can not travel through a vacuum (empty space).Įlectromagnetic Waves - Do not require a physical medium through which to travel. Mechanical Wave - A wave that requires a physical medium through which to travel. This fact allows us to put all waves into two broad categories: Not all waves actually require a physical medium through which to travel. Medium - The material through which a wave travels ![]() ![]() Wave - A periodic disturbance that transfers energy Let's start with a couple of basic definitions: ![]()
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