Electric motors come in all shapes and sizes and have found use in a vast range of applications for many decades. With the foreseeable widespread replacement of internal combustion engines by electric drive trains in vehicles, electric motors will soon be seen as the primary way to create mechanical motion. That alone makes them worth a closer look.  

Electric motors can be found wherever electrical energy is to be turned into mechanical energy of whatever kind. They have many advantages over internal combustion engines and other non-electrical methods for producing mechanical energy such as water mills and windmills. Principal among these are small footprint, low weight, long service life and high efficiency. In larger machines, efficiency can be considerably more than 90%. The tiniest examples can be found in luxury non-mechanical watches. At power levels up to 100 W, we find the conventional ‘universal’ motors, and special variants such as stepper motors, servos, shaded-pole m...