EMF stands for Electromotive force. EMF is measured in units of volts.
Only the relative direction they are moving. EMF, measured in Volts, travels along a conductor, perhaps because a magnetic field has built up around the conductor. When that magnetic field collapses,...
alternators are used in cars and generators are used for you know everything else
alternators produce AC which is rectified by diodes if DC is needed. dynamos produce DC by using a commutator