title: Electromechanical coupling coefficient
text: # Electromechanical coupling coefficient
  
  The electromechanical coupling coefficient is a numerical measure of the conversion efficiency between electrical and acoustic energy in piezoelectric materials.
  
  Qualitatively the electromechanical coupling coefficient, k, can be described as:
  
      $k^{-2}={\frac {1}{\mbox{ energy converted per input energy}}}$
  