Electrical Engineering · Question Bank

DC Motors

218 of 285 questions match · page 4 of 11. Answer in your head first, then check the solution.

📘 EE Mock Board Exam
TypeAll 218Problem solving 10Objective 208
DifficultyAll 285Easy 218Medium 54Hard 13
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#61📘 EE Pocket Reviewer RojasEasy
Which of the following dc motors has the highest no load speed?
ASeries motors
BShunt motors
CCumulative compound motors
DDifferential compound motors
#62📘 EE Pocket Reviewer RojasEasy
What is the function of the commutator in dc motor?
ATo prevent sparking
BTo reduce friction
CTo convert ac to dc
DTo convert dc to ac
#63📘 EE Pocket Reviewer RojasEasy
A series motor is best suited to drive which of the following loads?
ALathes
BMachine tools
CShears and punches
DCranes and hoists
#64📘 EE Pocket Reviewer RojasEasy
The starting torque of a dc motor is independent of the following?
AFlux
BSpeed
CArmature current
DFlux and armature current
#65📘 EE Pocket Reviewer RojasEasy
Which one is a cause for intermittent sparking at the brushes of a dc motor?
AOpen armature coil
BLoose coupling at the shaft
CIncorrect supply voltage
DIntermittent loads
#66📘 EE Pocket Reviewer RojasEasy
Which of the following dc motors will be used to - drive intermittent high torque loads?
AShunt motors
BSeries motors
CCumulative compound motors
DDifferential compound motors
#67📘 EE Pocket Reviewer RojasEasy
How will you reverse the direction of rotation of a self-excited dc motors?
AInterchange the supply connections
BInterchange the armature connections
CInterchange both the armature and field connections
DOpen the field terminals at starting instant
#68📘 EE Pocket Reviewer RojasEasy
What is the purpose of using carbon brushes in dc motors?
ATo prevent sparking during commutation
BTo prevent overheating on the armature windings
CTo brush off carbon deposits in the commutator
DTo provide a path for current to flow
#69📘 EE Pocket Reviewer RojasEasy
What is the purpose of retardation test on dc motors?
ATo determine stray losses
BTo determine copper losses
CTo determine friction losses
DTo determine iron losses
#70📘 EE Pocket Reviewer RojasEasy
Counter EMF is measured using one of the following units. Which one?
AVolt
BKilowatt-hour
CAmpere-hour
DHorsepower
#71📘 EE Pocket Reviewer RojasEasy
For which of the following applications dc motors are still preferred?
AHigh efficiency operation
BReversibility
CVariable speed drive
DHigh starting torque
#72📘 EE Pocket Reviewer RojasEasy
Which of the following dc motors are not used in belt driven loads?
ASeries motors
BShunt motors
CCumulative compound motors
DDifferential compound motors
#73📘 EE Pocket Reviewer RojasEasy
What is the reason why series motors are best suited for traction work applications?
ATorque is proportional to the square of the current and speed is inversely proportional to the torque
BTorque is proportional to the square of the armature current and speed is proportional to the torque
CBoth speed and torque are proportional to the square of the armature current
DBoth speed and torque are proportional to the armature current
#74📘 EE Pocket Reviewer RojasEasy
In a dc motor, the ratio \(E_b/V\) is an indication of which of the following?
ASpeed regulation
BEfficiency
CRatio of starting torque to rated torque
DPower losses
#75📘 EE Pocket Reviewer RojasEasy
A dc shunt motor is running with a certain load. What is the effect if an external resistance is added in the field circuit?
AThe motor will stop running
BThe motor speed will decrease
CThe motor speed will increase
DThe armature current will be reduced
#76📘 EE Pocket Reviewer RojasEasy
Which of the following dc motor parts can sustain the maximum high temperature rise?
ACommutator
BSlip rings
CArmature windings
DField windings
#77📘 EE Pocket Reviewer RojasEasy
What is the reason why dc motors are still used in industrial applications up to today?
AIt provides fine speed controls
BIt has a cheaper cost than ac motors
CIt has a simple and rugged construction
DIt has a higher efficiency than ac motors
#78📘 EE Pocket Reviewer RojasEasy
When a dc motor is overloaded, the motor is in danger because of which of the following?
ACommutator segments are getting overheated
BArmature windings are getting overheated
CMotor bearings are getting overheated
DStarting resistance are getting overheated
#79📘 EE Pocket Reviewer RojasEasy
What type of dc motors are suitable to drive elevators?
ASeries motors
BShunt motors
CCumulative compound motors
DDifferential compound motors
#80📘 EE Pocket Reviewer RojasEasy
What will happen to the speed of a shunt motor if the load is removed?
AIt will slow down
BIt will stop
CIt will speed up slightly
DIt will remain at the same speed

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