A 220 V, DC shunt motor is operating at a speed of 1440 rpm. The armature resistance is 1.0 $$\Omega$$ and armature current is 10 A. of the excitation of the machine is reduced by 10%, the extra resistance to be put in the armature circuit to maintain the same speed and torque will be

A separately excited DC motor runs at 1500 rpm under no-load with 200 V applied to the armature. The field voltage is maintained at its rated value. The speed of the motor, when it delivers a torque of 5 Nm, is 1400 rpm as shown in the figure. The rotational losses and armature reaction are neglected. For the motor to deliver a torque of 2.5 Nm at 1400 rpm the armature voltage to be applied is

A separately excited DC motor runs at 1500 rpm under no-load with 200 V applied to the armature. The field voltage is maintained at its rated value. The speed of the motor, when it delivers a torque of 5 Nm, is 1400 rpm as shown in the figure. The rotational losses and armature reaction are neglected. The armature resistance of the motor is,

Figure shows the extended view of a $$2$$ pole $$dc$$ machine with $$10$$ armature conductors. Normal brush positions are shown by $$A$$ and $$B,$$ placed at the inter polar axis. If the brushes are now shifted, in the direction of rotation to $$A'$$ and $$B'$$ as shown, the voltage waveform $${V_{A'B'}}$$ will resemble