When an electric current is applied to the Piezoelectric Crystal, it produces

• A. Sound waves
• B. Light waves
• C. Magnetic fields
• D. Heat

Answer: (D)

When a piezoelectric crystal is driven with an electric field, it undergoes rapid deformation in response—the inverse piezoelectric effect. This mechanical vibration creates waves in the surrounding medium, which we perceive as sound or ultrasound depending on the frequency. Light is not generated by this effect, and magnetic fields aren’t the primary outcome either. Heat can arise from losses in the material, but it isn’t the intended function of a piezoelectric transducer—the main purpose is to convert electrical energy into mechanical (sound) energy.