Which the purpose for DC Motor to use back EMF? State the most important purpose?

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 and agree with answer colleagues and the God bless

the back emf developed along coil reduce current flow through it,, and will help coil stay away from getting hot fast.  :)

Thank you for the invitation

Agreed with answer colleagues

With greetings and appreciation

The induced EMF developed when the rotating conductors of the armature between the poles of magnet, in a DC motor, cut the magnetic flux, opposes the current flowing through the conductor, when the armature rotates, is called back EMF. Its value depends upon the speed of rotation of the armature conductors. In starting, the value of back EMF is zero.