parallel with the field windings

series with the field windings

parallel with the load

series with the armature winding

copper loss

eddy current loss

hysteresis loss

windage loss

reduce the overall mass

insulate core

reduce the eddy current loss

all the above

imperfect contact

severe sparking

rough commutator surface

any one of the above

low voltage, low current

high voltage, high current

low voltage, high current

high voltage, low current