Brushes of D.C. machines are made of_________?
Correct answer: A. carbon
- A. carbon
- B. soft copper
- C. hard copper
- D. all of above
Explanation
Carbon or graphite brushes are the usual choice because they provide suitable conductivity while limiting commutator wear and sparking. Copper brushes are used only in special low-voltage, high-current applications, so the standard answer is carbon.
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