$8\mathrm{.}5\mathrm{.}2$ Speed Control Methods

Example: Con$$ider a $100-$hp$,250-V,1200$ rpm separately excited dc motor with an armature resistance of $0\mathrm{.}03$ and a field resistance of $41\mathrm{.}67.$ The motor is initially running with $V_A=250V,I_A=120A,$ and $n=1103rpm,$ while supplying a constant$-$torque load. What will the speed of this motor be if $V_A$ is reduced to $200$ V $?$