back emf www.electreng.blogspot.com
The induced emf developed when the rotating conductors of
the armature between the poles of magnet, in a DC motor,
cut the magnetic flux, opposes the current flowing through
the conductor, when the armature rotates, is called back
emf. Its value depends upon the speed of rotation of the
armature conductors. In starting, the value of back emf is
zero.