What type of device converts energy from one form to another?

A transducer is a device that converts energy from one form to another, making it essential in various applications across different fields, such as electronics, communication, and instrumentation. For instance, a microphone is a transducer that converts sound waves (acoustic energy) into electrical signals, while a loudspeaker does the reverse by converting electrical signals back into sound waves.

The term "converter" could be seen as somewhat accurate, as it also implies a change in energy forms, such as a power converter changing AC (alternating current) to DC (direct current). However, it generally refers to electrical devices and is not as broad or universally applicable as the concept of a transducer.

It's also important to differentiate transducers from amplifiers. While amplifiers take a signal and increase its strength without altering its form, transducers genuinely transform one type of energy into another. Lastly, sensors, while related to measurement and detection of changes in physical properties (like temperature, pressure, etc.), do not inherently convert one type of energy into another; they often provide data about the physical condition without energy transformation.

This is why "transducer" is the most suitable choice to define a device that performs energy conversion.