Sensors and interfacing – definition of a transducer in instrumentation A transducer is a device that:

Introduction / Context:
Instrumentation and control systems rely on transducers to translate real-world phenomena into electrical signals that electronics can process. Recognizing the correct definition is foundational for sensor selection and signal conditioning.

Given Data / Assumptions:

• “Physical variable” may include temperature, pressure, light, motion, force, etc.
• Electronics typically require a voltage, current, resistance, or frequency to represent that variable.

Concept / Approach:
A transducer performs energy conversion from one domain to another. In measurement systems we usually mean conversion from a physical domain to an electrical domain (e.g., thermocouple, strain gauge, photodiode). Actuators are the converse (electrical to physical). Data processing/storage functions are not transduction.

Step-by-Step Solution:

Verification / Alternative check:
Textbooks define a transducer as a device that converts energy from one form to another; in sensor contexts the conversion is to an electrical signal proportional to the measurand.

Why Other Options Are Wrong:

• Converts analog data to meaningful data: That is signal processing, not transduction.
• Controls a physical variable: That describes an actuator or controller.
• Stores and processes digital data: That describes a computer or digital system, not a transducer.

Common Pitfalls:

• Confusing sensors (transducers) with actuators or with processing electronics.

Final Answer:
converts a physical variable to an electrical variable