Alternator energy consumption?

[strathcona93]

Would someone be able to explain the physics behind how an alternator consumes energy? Obviously there is friction but what force is pushing back on the rotor? How does getting the electrons moving in the wire push back on the magnetic core?

 

[Andrew Mason]

Would someone be able to explain the physics behind how an alternator consumes energy? Obviously there is friction but what force is pushing back on the rotor? How does getting the electrons moving in the wire push back on the magnetic core?

The force is magnetic. The increase of an electric current creates a magnetic field that opposes the increase (Lenz's Law). The increase of electric current in the stator windings causes the magnetic field of those windings to build up and make it harder for the rotor (which is a magnet) to turn.

AM