Unlike other treatments of sensors or actuators, this book approaches the devices from the point of view of the fundamental coupling mechanism between the electrical and mechanical behaviour. The principles of operation of the solenoid are the same in both cases, and this book thus treats them together. It begins with a discussion of systems analysis as a tool for modelling transducers, before turning to a detailed discussion of transduction mechanisms. The whole is rounded off by an input/output analysis of transducers.