Question

why do we use commutator in DC motor
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Answer 1

Answer:

used to maintain unidirectional torque i.e. it only reverses direction of current flow.

Explanation:

Answer 2

Answer:

To keep the torque on a DC motor from reversing every time the coil moves through the plane perpendicular to the magnetic field, a split-ring device called a commutator is used to reverse the current at that point.