AP ECET ELECTRICAL AND ELECTRONICS ENGINEERING (EEE) Multiple Choice Questions (MCQs)
AP ECET Electrical and Electronics Engineering (EEE) - Unit IV: A.C. Machines
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46. The construction of an alternator is based on:
- a) Faraday’s Law of Electromagnetic Induction
- b) Ampere's Law
- c) Lenz's Law
- d) Coulomb's Law
Answer: a) Faraday’s Law of Electromagnetic Induction
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47. The EMF generated in an alternator is proportional to:
- a) Speed of rotation and flux
- b) Flux only
- c) Speed of rotation only
- d) Voltage only
Answer: a) Speed of rotation and flux
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48. The synchronous speed of an alternator depends on:
- a) Voltage and flux
- b) The number of poles and frequency
- c) Frequency and resistance
- d) Number of poles and power factor
Answer: b) The number of poles and frequency
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49. The regulation of an alternator is defined as:
- a) The difference between no-load and full-load voltage
- b) The ratio of full-load voltage to no-load voltage
- c) The efficiency at full load
- d) The speed at no-load condition
Answer: a) The difference between no-load and full-load voltage
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50. The V-curve of a synchronous motor shows:
- a) The relationship between speed and power factor
- b) The relationship between excitation and power factor
- c) The relationship between torque and current
- d) The relationship between current and voltage
Answer: b) The relationship between excitation and power factor
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51. An inverted V-curve for a synchronous motor occurs when:
- a) Over-excitation leads to a higher power factor
- b) Under-excitation leads to a higher power factor
- c) Excitation is increased
- d) Excitation is decreased
Answer: b) Under-excitation leads to a higher power factor
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52. The efficiency of a synchronous motor depends on:
- a) The load and voltage applied
- b) The power factor and mechanical losses
- c) The excitation voltage
- d) All of the above
Answer: d) All of the above
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53. The slip of a three-phase induction motor is defined as:
- a) The ratio of rotor speed to synchronous speed
- b) The difference between synchronous speed and rotor speed
- c) The difference between stator speed and rotor speed
- d) The ratio of stator speed to rotor speed
Answer: b) The difference between synchronous speed and rotor speed
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54. In a three-phase induction motor, the torque is directly proportional to:
- a) Slip
- b) Rotor resistance
- c) Square of the slip
- d) Frequency
Answer: a) Slip
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55. The efficiency of a three-phase induction motor is highest when:
- a) The motor is at no load
- b) The slip is zero
- c) The motor is running at rated load
- d) The slip is maximum
Answer: c) The motor is running at rated load
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56. The speed of a three-phase induction motor can be controlled by:
- a) Varying the voltage supply
- b) Changing the number of poles
- c) Changing the resistance in the rotor
- d) All of the above
Answer: d) All of the above
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57. The main disadvantage of a single-phase induction motor is:
- a) Low efficiency
- b) It requires a capacitor to start
- c) Low starting torque
- d) High slip
Answer: c) Low starting torque
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58. The types of single-phase induction motors include:
- a) Split-phase, capacitor start, and shaded pole
- b) Synchronous and asynchronous
- c) Universal and series
- d) All of the above
Answer: a) Split-phase, capacitor start, and shaded pole
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59. A single-phase commutator motor is commonly used in:
- a) Industrial applications
- b) Domestic appliances
- c) High-voltage applications
- d) None of the above
Answer: b) Domestic appliances
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60. The principle of operation of a single-phase commutator motor is similar to:
- a) A DC motor
- b) A synchronous motor
- c) An induction motor
- d) A transformer
Answer: a) A DC motor
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