can an electric motor be used as a generator if turned backwards counter clockwise?

Answer 1

Yes, but only if the motor contains permanent magnets around which the coils would turn.

Some motors have electromagnets, and would be useless for generating electricity unless an outside source of power was provided to create the magnetic field.

Answer 2

No, there is a little more to it than that. In an electric motor outside or external power is supplied to the stationary field windings of the motor which " excites the field ". Then due to the attraction / repulsion of magnetic fields, cause the rotor which is made up of multiple individual insulated segments, and free to rotate in it's bearings, to turn. You plug the electric motor in, electricity excites the field of the motor causing the rotor to turn. You then harness the turning moment or the rotor by typically having a drive belt pulley mounted to it and a drive belt to spin what you want to turn.
If you were to just spin an electric motor, ( direction of rotation is irrelevant ) you would get nothing at all accomplished, much less generate power. An electric motor requires external power to make it work, something has to excite the field !!! An alternator on a car will not charge the cars battery unless the battery supplies power to excite the field of the alternator. Once excited and with the rotor spinning in this field, it will then charge your cars battery.
Old cars had generators and not alternators to keep the battery charged. A generator will produce current without an outside source to excite the field due to it's construction using permanent magnets. The running car spun the generators rotor with a drive belt, and the rotor spinning within
the permanent magnetic field produced D.C. current. An old car generator can be made into an D.C. motor but not vice versa. With a generator, the current you created is discharged or picked up from the field windings and sent to the battery. By reversing the direction of the current and by using a battery to excite the field, this in turn will cause the rotor to turn on it's own and you now have a motor.
Mechanically spinning the rotor of a generator causes the field windings to generate current for whatever use. Consequently, by reversing the direction and introducing power from a battery directly into the field windings at the point where current was discharged from it before, this now causes the rotor to turn with the ability to drive something else. Hence, you have created an D.C. Motor from a generator !!!

Answer 3

Absolutely. The theory behind both is amazingly similar. DC motors are also considered electro-motive transducers, meaning you can input current to get torque, or input torque to get current. An actual DC generator might have differences that enhance its power producing capability, but it will still work as a motor if you apply current to it.

Answer 4

a generator can be turned into a motor so maybe the reverse is true