All Free Electrical Engineering MCQs with Answers
Every Electrical Engineering question in the bank, across all chapters, each with the correct answer and a written explanation. Free and unlimited, with no account needed.
3,143 questions · page 53 of 158
- A. End play
- B. Air gap
- C. Insulation in rotor
- D. Balancing of rotor
Explanation: A universal motor runs at very high speed, so even slight rotor unbalance produces substantial centrifugal vibration and stress.
Correct answer: Balancing of rotor- A. good power factor
- B. high efficiency
- C. minimum cost
- D. high starting torque
Explanation: The repulsion-start induction-run motor combines repulsion-motor starting with induction-motor running, giving it a high starting torque.
Correct answer: high starting torque- A. from main pole to shaded pole
- B. from shaded pole to main pole
- C. either of the above depending on voltage
- D. either of the above depending on power factor
Explanation: The shaded portion reaches its induced magnetic effect later than the unshaded portion, producing a sweeping field from the main, unshaded…
Correct answer: from main pole to shaded pole- A. Resistance start
- B. Capacitor start capacitor run
- C. Shaded pole
- D. Universal
Explanation: Shaded-pole motors are simple, inexpensive and suitable for the very small power needed in phonographs and similar timing or household…
Correct answer: Shaded pole- A. Universal motor
- B. Repulsion motor
- C. Synchronous motor
- D. Reluctance motor
Explanation: A universal motor is designed so that reversing the supply polarity reverses both armature and field currents, keeping the torque…
Correct answer: Universal motor- A. air capacitor
- B. paper spaced oil filled type
- C. ceramic type
- D. a.c. electrolytic type
Explanation: The running capacitor remains connected continuously, so it is commonly a reliable paper-spaced, oil-filled capacitor.
Correct answer: paper spaced oil filled type- A. thick wire placed at the bottom of the slots
- B. thick wire placed at the top of the slots
- C. thin wire placed at the top of the slots
- D. thin wire placed at the bottom of the slots
Explanation: The auxiliary winding uses thin, high-resistance wire and is placed toward the top of the slots, while the main winding uses thicker wire.
Correct answer: thin wire placed at the top of the slots- A. 0.6 power factor lagging
- B. 0.8 power factor lagging
- C. 0.8 power factor leading
- D. unity power factor
Explanation: A single-phase induction motor normally draws magnetizing current and therefore operates with a lagging power factor, commonly around 0.6…
Correct answer: 0.6 power factor lagging- A. Shaped pole motor
- B. Split phase motor
- C. Capacitor start motor
- D. Capacitor run motor
Explanation: The running capacitor remains in circuit in a capacitor-run motor and continuously supplies reactive current, improving the phase…
Correct answer: Capacitor run motor- A. Reluctance motor
- B. Series motor
- C. Repulsion motor
- D. Universal motor
Explanation: A reluctance motor is valued for nearly constant speed and simple, reliable operation, making it suitable for timing devices and control…
Correct answer: Reluctance motor- A. zero slip
- B. negative slip
- C. positive slip
- D. all of the above
Explanation: A Schrage motor permits operation below, at, or above synchronous speed, corresponding respectively to positive, zero, and negative slip.
Correct answer: all of the above- A. A.C. only
- B. D.C. only
- C. either A.C. or D.C.
- D. none of the above
Explanation: A universal motor has its field and armature connections arranged so that torque remains unidirectional with either supply type.
Correct answer: either A.C. or D.C.- A. Shaded pole motor
- B. Hysteresis motor
- C. Two value capacitor motor
- D. Universal motor
Explanation: A hysteresis motor runs smoothly and quietly at nearly constant speed, making it suitable for tape recorders and other timing…
Correct answer: Hysteresis motor- A. inherently self-starting with high torque
- B. inherently self-starting with low torque
- C. inherently non-self-starting with low torque
- D. inherently non-self-starting with high torque
Explanation: A single-phase induction motor produces a pulsating magnetic field whose forward and backward torque components cancel at standstill.
Correct answer: inherently non-self-starting with low torque- A. Electric shavers
- B. Refrigerators
- C. Signalling and timing devices
- D. Lifts and hoists
Explanation: Reluctance motors are valued for nearly constant speed and simple construction, so they are used in signalling, timing, and control…
Correct answer: Signalling and timing devices- A. universal motor
- B. D.C. shunt motor
- C. single-phase capacitor run motor
- D. 3-phase synchronous motor
Explanation: A capacitor-run motor provides reasonably good starting torque, smooth operation, and nearly constant speed, which suit small lathes.
Correct answer: single-phase capacitor run motor- A. hysteresis loss
- B. magnetisation of rotor
- C. eddy current loss
- D. electromagnetic induction
Explanation: A hysteresis motor develops torque because the rotor magnetisation lags the rotating stator field, producing hysteresis torque associated…
Correct answer: hysteresis loss- A. D.C. shunt motor
- B. Schrage motor
- C. Repulsion start and induction run motor
- D. Universal motor
Explanation: The Schrage motor has a series-type commutator construction that provides very high starting torque.
Correct answer: Schrage motor- A. lagging
- B. always leading
- C. unity
- D. unity to 0.8 leading
Explanation: The stator magnetising current of a single-phase induction motor lags the supply voltage, so its power factor is normally lagging.
Correct answer: lagging- A. toys
- B. hair dryers
- C. circulators
- D. any of the above
Explanation: Shaded-pole motors are inexpensive, compact, and suitable for small loads such as toys, hair dryers, and circulators.
Correct answer: any of the above