Electrical Machines
A 240 V, dc shunt motor draws 15 A while supplying the rated load at a speed of 80 rad/s. The armature resistance is 0.5 W and the field winding resistance is 80 W. The external resistance to be added in the armature circuit to limit the armature current to 125% of its rated value is

 31.9 Ω
 31.1 Ω
 15.1 Ω
 15.9 Ω

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Electrical Machines
With the increase in speed of a DC motor

 both back emf as well as line current fall.
 both back emf as well as line current increase.
 back emf increases but line current falls.
 back emf falls and line current increases.

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