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This set of Electrical and Electronics Engineering Multiple Choice Questions & Answers (MCQs) focuses on Electrical And Electronics Engineering Set 3
Q1 | ____ dc machine are most common.
- 2-pole
- 4-pole
- 6-pole
- 8-pole
Q2 | The armature winding of a dc machine is place on rotor to_____.
- save iron
- reduce losses
- improve commutation
- reduce armature reaction
Q3 | The yoke of a dc machine carries ____pole flux.
- the
- one-half of
- two times the
- none of the above
Q4 | A 4-pole dc machine has ____ magnetic circuits.
- 2
- 8
- 4
- none of above
Q5 | The field structure of a dc machine uses ____.
- salient pole arrangement
- non-salient pole arrangement
- both a and b
- none of the above
Q6 | ____ together are called stray losses
- copper and iron losses
- iron and mechnical losses
- field copper and iron losses
- frictional and copper losses
Q7 | The armature conductors of 6 pole, lap wound D.C. generator are divided into
- 2 parallel paths
- 4 parallel paths
- 3 parallel paths
- 6 parallel paths
Q8 | A 30W, 300V D.C. shunt genrator has armature and field resistances of 0.05Ω and 100Ω respectively. What is generated e.m.f.?
- 295.25v
- 311.25v
- 305.15v
- none of the above
Q9 | The commutator of D.C. geenrator acts as ___
- an amplifier
- a rectifier
- a load
- none of the above
Q10 | A 4 pole , lap wound D.C. shunt generator has an armature winding consisting of 220 turns each of 0.004Ω. The armature resistance is ___
- 0.5Ω
- 1Ω
- 0.025Ω
- 0.055Ω
Q11 | Wave wound genrators provide
- less current but more voltage
- more current but less voltage
- more current but less voltage
- none of the above
Q12 | A D.C. motor is still used in industrial applications because it____.
- is cheap
- is simple in construction
- provides fine speed control
- none of the above
Q13 | The field poles and armature of a D.C. machine are laminated to___.
- reduce the weight of the machine
- decrease the speed
- reduce eddy currents
- reduce armature reaction
Q14 | The value of back EMF in a DC motor is maximum at ____.
- no load
- full load
- half of full load
- none of the above
Q15 | The mechanical power developed in a dc motor is maximum when back emf (Eb) is equal to ------the applied voltage (V)
- twice
- half
- one third
- none of the above
Q16 | When the speed of dc motor increases , its armature current ----
- increases
- decreases
- remains constant
- none of the above
Q17 | The amount of back emf of a shunt motor will increase when
- the load is increased
- the field is weakened
- the field is strengthened
- none of the above
Q18 | The speed of a dc motor is
- directly propotional to flux per pole
- inversely propotional to flux per pole
- inversely propotional to applied voltage
- none of the above
Q19 | The torque developed by a dc motor is directly propotional to---
- flux per pole x armature current
- armature resistance x applied voltage
- armature resistancex armature current
- none of the above
Q20 | The shaft torque in a DC motor is less than total armature torque because of ____in the motor
- cu losses
- field losses
- iron and friction lossees
- none of the above
Q21 | In a DC motor the brushes shifted from the mechanical nuetral plane in a direction opposite to the rotation to _____.
- decrease the speed
- increase the speed
- reduce sparking
- produce flat characteristics
Q22 | The speed of a ____ motor is practically constant
- cumulative compound
- series
- differential compound
- shunt motor
Q23 | ____ motor is a variable speed motor.
- series
- shunt
- cumulatively compounded
- differetial compounded
Q24 | The most commonly used method of speed control of a DC motor is by varying ____.
- voltage applied to a motor
- field control
- effective number of conductors in series
- armature circuit resistance
Q25 | The running speed of a DC series motor is basically determined by _____.
- field excitation
- load
- armature resistance
- none of the above