A permanent magnet dc commutator motor has a no load speed

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A permanent magnet dc commutator motor has a no load speed of 6000 rpm when connected to a 120 V dc supply. The armature resistance is 2.5 ohms and other losses may be neglected. The speed of the motor with supply voltage of 60 V developing a torque 0.5 Nm, is _______ rpm .

1. 1337 rpm
2. 2673 rpm
3. 1671 rpm
4. 773 rpm

Correct Option: B

We know, E_b = KN

Here , K =	1		V
	50		rpm

I_a2 = 2.62 A , E_b2 = 53.45

∴ N =	53.45	× 6000 = 2673 rpm.
	120