Use to the filed Resistance when the filed resistance of DC shunt motor increase the filed current  then the flux is also decrease of the and armature that against the emf is decrees

Current  and torque is also in crease this circuit and the motor speed is control when the filed of the resistance increase speed also and when the filed resistance speed the motor of decrease and the end the speed of DC motor are control

DC motor control of motor to use the changing the voltage to the control of speed the DC Motor the voltage source to

 

the connected the armature as the voltage the armature current in crease to use for the control the DC Motor

DC motor control the use of the armature resistance in this the armature resistance to use the increase the current of

armature and induced to the torque in this armature will be also to use torqe the DC Motor control easy and useful very

easy the base of the speed but due to the mehtode is used is very easy