7-6. The power converted from one form to another within a dc motor was given byUse the eq...

7-6. The power converted from one form to another within a dc motor was given by

Use the equations for E_A and

[Equations (7-38) and (7-49)] to prove that

that is,

prove that the electric power disappearing at the point of power conversion is exactly equal to the mechanical power appearing at that point.