Question

The effiency of a dc motor when developing maximum power will be about

Answer 1

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Answer 2

The efficiency of a dc motor when developing maximum power will be about

DC motor is an electrical machine which converts DC Current into Mechanical Energy.

Back emf occurs in DC motors which is around 50%  at maximum power output, .

Back-emf is caused by the armature spinning and generating a voltage which opposes the supply voltage

So generally the efficiency of a dc motor when developing maximum power will be about less than 50%