@Dominions Son
Dynamo is a generic term for a device that generates electricity from mechanical energy. The term gets used even in the electric utility industry with grid scale generators.
Sorry, the generic term is 'generator'
The alternator in a modern car is technically a type of dynamo.
No, an alternator generates AC power, a dynamo generates DC power. The alternator in a car has a rectifier block attached to convert the AC to DC
Also, all electric motors are dynamos. They are fully reversible.
Sorry, wrong again. Many motors can be used as generators, but some types cannot - for example, variable reluctance stepper motors can't (but permanent magnet steppers can), nor can shaded-pole induction motors (nor, I think, any single-phase induction motor). Universal AC/DC motors are also problematic - there needs to be noticeable remnant magnetism in the armature to allow it to start up and the load has to be matched to the winding type, or else the vestigial current generated by the remnant magnetism will not be fed back to increase the field. Induction motors are a bit of an odd case - without power applied, zip, but with power applied, if you force them to rotate faster than their normal running speed, they will feed power back into the supply. However, if there's a variable-speed or other) controller involved, it depends on the design of the controller as to whether useful power can be generated, the power just gets dumped (dynamic braking), or the controller lets out the magic smoke.
One interesting application of the motor-as-generator principle is the so-called 'rotary transformer', which is effectively a multi-phase (typically three-phase) induction motor run from a single phase (it needs a phase-shift network to start it, which is typically switched out once it's started), generating the extra phases in a single device used as both a motor and generator simultaneously. Great if you've got three-phase shop tools but don't want to spend the $$$ for a three-phase supply.
