Which device changes one form of energy into another?

A transducer is a device specifically designed to convert one form of energy into another. This conversion can take place between different types of energy such as electrical energy, mechanical energy, thermal energy, or even light. For instance, a common example is a microphone, which converts sound (mechanical energy) into electrical signals, or a loudspeaker, which does the opposite by taking electrical signals and converting them back into sound.

In the context of energy systems, transducers play a crucial role in measurement and control applications, allowing various forms of data to be processed and utilized effectively. This capability is foundational in many engineering and technological processes, making transducers vital components in a variety of systems.

Considering the other options, sensors are designed to detect and measure physical properties or conditions but do not inherently convert energy from one form to another; rather, they provide output signals based on the quantity they measure. Amplifiers are used to increase the strength of an electrical signal without changing its form, and actuators convert electrical energy into mechanical motion but are not primarily engaged in a general energy conversion process.