This document discusses electric motors and DC motors specifically. It provides information on: 1. The basic components and principles of DC motors, including how a current-carrying coil in a magnetic field produces torque. 2. How back electromotive force (EMF) regulates motor speed as the armature rotates in the magnetic field. 3. Equations for motor voltage, torque, speed, and characteristics like torque-current curves for series, shunt, and compound motors. 4. Methods for controlling motor speed including changing the flux, armature resistance, or applied voltage. Starters are also discussed to limit starting current.