The generator and alternator are two devices that convert mechanical energy into electrical energy. Both have the same principle of electromagnetic induction; the only difference is their construction. The generator has a stationary magnetic field and rotating conductor that rolls on the armature with slip rings and brushes riding against each other. Hence, it converts the induced emf into DC for external load. An alternator has a stationary armature and rotating magnetic field for high voltages, but a rotating armature and the stationary magnetic field are used for low-voltage output.