DC Machines MCQs | DC Machines Short Questions and Answers

Sports GK Questions and Answers 2024 (Latest Updated)

Awards & Honours GK Questions 2024 (Latest Updated)

Questions
41 Carbon brushes are used in electric motors to
A Prevent sparking during commutation
B Provide a path for flow of current
C Brush off carbon deposits on the commutator
D None 0f these

Answer: Provide a path for flow of current
42 Interpoles in dc motors are used for
A Increasing the speed of motor
B Reducing sparking at the commutation
C Decreasing the counter emf
D Converting armature current to dc

Answer: Reducing sparking at the commutation
43 Small dc motors upto 5 HP usually have
A 2 poles
B 4 poles
C 6 poles
D 8 poles

Answer: 2 poles
44 The resistance of the starter of a 220 v, 5 HP dc shunt motor is of the order of
A 0.01Ω
B 0.1Ω
C 1Ω
D 10Ω

Answer: 10Ω
45 A dc motor can be easily identified by
A Yoke
B Size of conductor
C Commutator
D Winding

Answer: Commutator
46 The back emf of a dc motor
A Adds to the supply voltage
B Regulates its armature voltage
C Helps in energy conversion
D Usually exceeds the supply voltage

Answer: Helps in energy conversion
47 In a dc motor, pole shoes are fixed to the magnet core by
A Set of screws
B Key
C Soldering
D Welding

Answer: Set of screws
48 In a dc motor, the ratio of back emf to supply emf is an indication of its
A Efficiency
B Speed regulation
C Starting torque
D Running torque

Answer: Efficiency
49 The value of diverter resistance for a series dc motor is of the order of
A 0.1Ω
B 2Ω
C 20Ω
D 400Ω

Answer: 0.1Ω
50 A large series motor is never started without some load on it, otherwise
A It draws very current
B It develops excessive speed and get damaged
C There results heavy sparking at the brushes
D Circuit gets open circuited

Answer: It develops excessive speed and get damaged
51 When load is removed, which of the following dc motors will run at excessively high speed?
A Shunt motor
B Series motor
C Cumulative compound motor
D Differential compound motor

Answer: Series motor
52 Speed of a motor may be varied by varying
A Field current
B Applied voltage
C Resistance in series with armature
D Any of these

Answer: Any of these
53 The speed of a dc motor is
A Always constant
B Directly proportional to back emf
C Directly proportional to flux
D Inversely proportional to the product of back emf and flux

Answer: Directly proportional to back emf
54 The highest speed attained by a dc shunt motor at rated flux is
A Infinity
B Higher than no load speed
C Equal to the no load speed
D Lower than the no load speed

Answer: Equal to the no load speed
55 A dc motor is preferred to an ac motor for the application in
A Low speed operation
B High speed operation
C Variable speed variation
D Fixed speed operation

Answer: Variable speed variation
56 If 220 V dc series motor is connected to a 220 V ac supply, then at will
A Not run
B Burn out
C Run smoothly
D Run with less efficiency and high sparking

Answer: Run with less efficiency and high sparking
57 Which of the following dc motor has approximately constant speed?
A Series motor
B Shunt motor
C Cumulatively compound motor
D Differentially compound motor

Answer: Shunt motor
58 The back emf of dc motor depends on
A Armature speed N
B Field flux ɸ
C Number of armature conductors
D All of these

Answer: All of these
59 When the direction of power flow reverses, a differentially compounded motor becomes
A Differentially compounded generator
B A shunt generator
C Cumulatively compounded generator
D A series generator

Answer: Cumulatively compounded generator
60 When the direction of power flow reverses, a cumulatively compounded motor becomes
A A differentially compounded generator
B A cumulative compounded generator
C A shunt generator
D A series generator

Answer: A differentially compounded generator

Random GK Questions

Q. In the electroplating of gold, the electrolyte used is
Q. In which year All India Trade Union Congress(AITUC) was formed ?
Q. Tear gas is
Q. Which one of the following countries is known as the Land of Thunderbolt?
Q. The common name of NaOH is
Q. Which state is the largest producer of iron ore in India ?
Assam Direct Recruitment Test Series

Computer Science Topics