🔍 Key Concepts

• Brush pressure and contact in DC motors • How poor electrical contact affects current flow and heating at the commutator • Typical symptoms of brush/commutator problems vs. load or magnetic problems

💭 Think About

• Think about what happens at the contact surface if the brush is not pressed firmly enough against the commutator: does resistance go up or down? • Which of the options is directly related to electrical contact at the brushes, rather than to the magnetic field or mechanical loading? • For each choice, ask: would this logically follow from intermittent or high‑resistance contact between brush and commutator?

✅ Before You Answer

• Identify which options are clearly related to magnetic field strength rather than contact issues • Eliminate any option that deals with generator loading instead of brush contact conditions • Focus on the effect that increased contact resistance and arcing (from loose brushes) would most likely produce among the choices