# Shear Wave Generation with EMATs

Shear waves have an inherent polarization direction depending on how they are generated. Pictured below are horizontally polarized shear waves propagating along the length of a plate.

Electromagnetic-acoustic transducers (EMAT) designed to generate shear waves actually vibrate the atoms within the material being investigated. When a wire is placed near to the surface of an electrically conducting object and is driven by a current at the desired ultrasonic frequency, eddy currents will be induced in a near surface region. If a static magnetic field is also present, these currents will experience Lorentz forces of the form

$F=J\times B$

F is the body force per unit volume, J is the induced dynamic current density, and B is the static magnetic induction.