DC Motors MCQs
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The speed of a dc motor is
- A. directly proportional to back emf and inversely proportional to flux
- B. inversely proportional to back emf and directly proportional to flux
- C. directly proportional to emf as well as flux
- D. inversely proportional to emf as well as flux
- Correct Answer: Option A
Condition for maximum power output for a dc motor is
- A. Eb = V
- B. Eb = V/2
- C. Eb = IaRa
- D. Eb = 1/2 IaRa
- Correct Answer: Option B
Terminal voltage equation for dc motor
- A. V = Eb IaRa
- B. V = Eb - IaRa
- C. Eb = V IaRa
- D. Eb = V - IaRa
- Correct Answer: Option A
Carbon brushes are used in electric motors to
- A. brush off carbon deposits on the commutator
- B. provide a path for flow of current
- C. prevent overheating of armature windings
- D. prevent sparking during commutation
- Correct Answer: Option B
The function of the commutator in a dc machine is
- A. to change alternating current to direct current
- B. to improve commutation
- C. for easy speed control
- D. to change alternating voltage to direct voltage
- Correct Answer: Option D
The rotating part of a dc motor is known as
- A. pole
- B. stator
- C. armature
- D. carbon brush
- Correct Answer: Option C
What is the effect produced by the electric motor?
- A. magnetic effect only
- B. magnetic as well as heating effect
- C. heating effect only
- D. heating as well as chemical effect
- Correct Answer: Option B