Electronics and Electrical Engineering 6

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Mechanical Engineering MCQ Question Papers: DRDO, ISRO, Interview

Subject: Electronics and Electrical Engineering 6

Part 6: List for questions and answers of Electronics and Electrical Engineering

Q1. Slip ring induction motor has
a) Low starting torque
b) Medium starting torque
c) High starting torque
d) None of these

Q2. The frequency of rotor current in an induction motor is
a) Slip times the frequency of stator current
b) Slip times the frequency of supply
c) One by slip times the frequency of stator current
d) One by slip times the frequency of supply

Q3. Slip of an induction motor increases with
a) Increase in current and decrease in torque
b) Increase in current and torque
c) Decrease in current and torque
d) Decrease in current and increase in torque

Q4. In an induction motor, rotor speed is always
a) Less than the stator speed
b) More than the stator speed
c) Equal to the stator speed
d) None of these

Q5. The frequency of the induced emf in an induction motor is
a) Greater than the supply frequency
b) Lesser than the supply frequency
c) Same as the supply frequency
d) None of these

Q6. The resultant flux in an induction motor is equal to the
a) Maximum value of flux due to any phase
b) Twice of the maximum value of flux due to any phase
c) 0.5 times the maximum value of flux due to any phase
d) 1.5 times the maximum value of flux due to any phase

Q7. Slip ring induction motor are employed only for
a) Speed control
b) High starting torque
c) Both (a) and (b)
d) None of these

Q8. The advantage of skewing in induction motor is
a) Motor runs smoothly as the magnetic hum is reduced
b) The tendency of the rotor teeth to remain under the stator teeth due to direct
magnetic attraction is reduced
c) More uniform torque is obtained while running
d) All of these

Q9. In induction motor, greater the number of poles
a) Lesser the speed
b) Greater the speed
c) Lesser the frequency
d) All of these

Q10. For induction motors
a) Should be essentially a constant speed motor
b) Its speed reduces to some extent with increase in load
c) Does not need to be synchronized
d) All of these

Q11. What is the shunt resistance component equivalent circuit obtained by no load test of an induction motor representative of ?
a) Windage and friction loss
b) Core loss only
c) Both 1 and 2
d) Copper loss

Q12. Induction motor operation depends on
a) Rotating magnetic field
b) Stationary magnetic field
c) Either of these
d) None of the above

Q13. Find the number of poles required, when the frequency is 50Hz and speed of the motor is 500 rpm?
a) 5
b) 10
c) 12
d) 24

Q14. Which of the following pairs is/are correct?
a) Open slot leakage flux is less
b) Closed slot leakage flux is high
c) Semi closed slot leakage flux is moderate
d) All of the above

Q15. Which of the following machines have highest power factor with respect to
magnetizing current?
a) Open slot type machines
b) Closed slot type machines
c) Semi closed slot type machine
d) Any of the above

Q16. Which of the following induction motor has the highest starting torque?
a) Squirrel cage induction motor
b) Slip ring induction motor
c) Same in both induction motors
d) None of the above

Q17. Which of the following motors is /are widely used?
a) Squirrel cage induction motor
b) Slip ring induction motor
c) Either of these
d) None of the above

Q18. A 4 pole 50 Hz induction motor is running at 1470 rpm. What is the slip value?
a) 0.2
b) 0.02
c) 0.04
d) 0.4

Q19. At stand still condition the value of slip is
a) 1
b) 0
c) Infinite value
d) Finite value

Q20. A 4 pole 50 Hz induction motor is running at 1470 rpm. The frequency of rotor current is
a) 50 Hz
b) 5 Hz
c) 1 Hz
d) 0 Hz

Part 6: List for questions and answers of Electronics and Electrical Engineering

Q1. Answer: c

Q2. Answer: b

Q3. Answer: b

Q4. Answer: a

Q5. Answer: c

Q6. Answer: d

Q7. Answer: c

Q8. Answer: d

Q9. Answer: c

Q10. Answer: d

Q11. Answer: b

Q12. Answer: a

Q13. Answer: c

Q14. Answer: d

Q15. Answer: b

Q16. Answer: b

Q17. Answer: a

Q18. Answer: b

Q19. Answer: a

Q20. Answer: c