The piezoelectric effect involves which of the following?

• A. Photovoltaic effect
• B. Thermoelectric effect
• C. Magnetostrictive effect
• D. Piezoelectric effect

Answer: (D)

The piezoelectric effect is the electrical response that occurs when certain crystals are mechanically stressed. When you apply pressure or deformation to these materials, electric charges appear on their surfaces, creating a voltage. This direct coupling between mechanical energy and electrical energy is why piezoelectric materials are used for sensors and ultrasonic transducers, and why applying an electric field can also cause the material to deform (the inverse piezoelectric effect). The other options describe different phenomena: photovoltaic effect is electricity generated by light, thermoelectric effect is voltage produced by a temperature difference, and magnetostrictive effect is strain produced by a magnetic field. So the piezoelectric effect specifically involves converting mechanical energy to electrical energy in those materials.