A piezoelectric material gives off a small electrical discharge when deformed.

• A. Ferroelectricity
• B. Electrostriction
• C. Piezoelectric effect
• D. Piezoelectricity

Answer: (D)

Mechanical deformation of a piezoelectric material creates a separation of electric charges, producing a small electric discharge. This is the direct conversion of mechanical energy into electrical energy known as the piezoelectric effect, and it's the phenomenon described by the term piezoelectricity. The observation fits because the material generates electricity in response to being stressed.

The other ideas describe different behaviors: ferroelectricity involves spontaneous polarization that can be reoriented by an electric field, not necessarily tied to mechanical deformation; electrostriction is a strain response to an electric field (or polarization) that occurs in all dielectrics and isn’t about generating charge from mechanical stress; the piezoelectric effect refers to the same direct process, but the broader label used here is piezoelectricity, which is why it’s the best match for the described discharge.