🔍 Key Concepts

• DC motor armature function and how current flows through the coils • What happens to current, heat, and torque if resistance in part of a winding suddenly becomes very low (short circuit) • Relationship between armature current, speed under load, and magnetic field strength

💭 Think About

• Think about what a short circuit does to current in an electrical component: does it increase or decrease current, and how does that affect heating? • If part of the armature is shorted, will the commutator and brushes see smoother current or more uneven, pulsating current? How would that affect sparking? • Under load, if the armature current becomes abnormally high, what usually happens to the speed of a DC motor?

✅ Before You Answer

• For each option, ask: would a short circuit make this effect worse or better? • Consider whether a shorted armature coil is more likely to cause overheating or cooler operation • Visualize the commutator: with shorted coils passing under the brushes, would you expect more or less sparking at the brush contact surface?