Light is an electromagnetic wave which are transverse in nature. They do however propagate through fluids, why is that?


1 Answer 1


Light is an electromagnetic wave, and they are indeed transverse in nature as the oscillation of the electric and magnetic fields is perpendicular to the direction of propagation of the wave. However, light waves are non-mechanical. This means that they do not require a physical medium in order to propagate. However, other mechanical transverse waves are unable to propagate through fluids due to their low shear strength.

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    $\begingroup$ Re. "If transverse waves are unable to travel through liquid"--where does this come from? $\endgroup$
    – user45664
    Commented Jan 29, 2019 at 17:13
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    $\begingroup$ @user45664 Shear strength is one of the forces that hold solids together. Fluids do not have much shear strength. In other words, in solids, molecules are tightly packed and have strong intermolecular binding forced. For transverse waves to travel through a medium, interatomic forces or shear forced should be strong, so that one particle is able to exert a pull on its nearest neighbor. In fluids, where intermolecular forces are not so strong, particles will slide past each other. That's why in liquid, transverse waves (mechanical) can't travel. $\endgroup$
    – Nikita
    Commented Jan 29, 2019 at 18:23

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