Copper brushes in D.C. machine are used_____________?
Correct answer: A. where low voltage and high currents are involved
- A. where low voltage and high currents are involved
- B. where high voltage and small cur-rents are involved
- C. in both of the above cases
- D. in none of the above cases
Explanation
Copper brushes have low contact resistance and are therefore suitable for low-voltage, high-current operation. Carbon brushes are generally preferred for higher-voltage machines because they improve commutation and limit current density.
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