1. Define field energy and co-energy.
2. Why do all practical energy conversion devices make use of the magnetic field as a coupling medium rather than an electric field?
3. What are the special applications where the electric field is used as a coupling medium for electromechanical energy conversion? Also explain why electric field coupling is preferred in such applications.
4. Elaborate the statement, "In a round rotor machine (uniform air-gap) with exciting coil placed in stator slots no reluctance torque is developed".