Piezo – electric transducers work when we apply _____________ to it.

Answer: Option A

Piezo-electric transducers operate based on the piezoelectric effect, which is the ability of certain materials to generate an electric charge when subjected to mechanical stress.

When a mechanical force is applied to a piezoelectric material, it produces a proportional voltage across its surfaces.

This property is widely used in sensors, actuators, and measurement instruments.

Option B (Vibrations) is incorrect because while vibrations may cause mechanical stress, it is the force behind the vibration that activates the piezoelectric effect.

Option C (Illuminations) and Option D (Heat) are unrelated to the working principle of piezoelectric transducers.

Therefore, the correct answer is Option A.