Which of the following brushes can be used for high values of current density ?
Correct answer: A. Metal graphite brushes
- A. Metal graphite brushes
- B. Hard carbon brushes
- C. Electro-graphitic brushes
- D. Natural graphite brushes
Explanation
Metal-graphite brushes can carry high current density because the metallic content gives them low electrical resistance, while graphite provides lubrication and satisfactory commutation. Hard carbon and natural graphite brushes are generally used at lower current densities.
Last updated
Practise Electrical Machines
1,061 free Electrical Machines MCQs from Electrical Engineering, each with the correct answer and an explanation. Unlimited attempts, no account needed.
Exams that ask Electrical Engineering questions like this
Electrical Engineering is on 2 papers prepared for on TestUstad, and all of them draw the same bank, so this question is worth knowing for every one of them.
Related questions
5 H.P., 50-Hz, 3-phase, 440 V, induction motors are available for the following r.p.m. Which motor will be the costliest ?
A 220 V D.C. generator is run at full speed without any excitation. The open circuit voltage will be_____________?
A 3-phase 440 V, 50 Hz induction motor has 4% slip. The frequency of rotor e.m.f. will be____________?
A 3-phase induction motor delta connected is carrying too heavy load and one of its fuses blows out. Then the motor______________?
A 3-phase induction motor stator delta connected, is carrying full load and one of its fuses blows out. Then the motor_______________?