Analysis of the electromechanical response of a piezoelectric bimorph operated by a constant voltage source is developed. The self-induced electric displacement field is considered using the extended Hamilton's principle for electromechanical systems. The tip deflection of a piezoelectric bimorph is affected by the self-induced displacement field. The short-circuit stiffness of a piezoelectric bimorph depends on the piezoelectric coupling coefficient.. The analytical results are validated with the experimental results published in literature.