A DC motor in a toy car shows normal current on the ammeter
PHYSICS · Single correct · CBSE · Physics · Magnetic Effects of Electric Current · Magnetic Effects of Electric Current
Problem
A DC motor in a toy car shows normal current on the ammeter, but the armature moves only through about half a turn and then stops each time it is nudged by hand. Which fault best explains this symptom?
(a) The permanent magnets have become too weak, so the field cannot sustain rotation.
(b) The brushes are worn out and lose contact after half a turn.
(c) One brush simultaneously touches both halves of the split ring.
(d) A section of the armature winding is broken, so torque is produced only for half a rotation.