D.C Motors Mcqs – (Electrical Engineering) MCQs Latest For FPSC, PPSC, NTS, KPPSC, SPSC & Other Tests
“ D.C Motors Mcqs “. Tab this page to check “Latest D.C Motors MCQs” for the preparation of competitive mcqs, FPSC mcqs, PPSC mcqs, SPSC mcqs, KPPSC mcqs, AJKPSC mcqs, BPSC mcqs, NTS mcqs, PTS mcqs, OTS mcqs, Atomic Energy mcqs, Pak Army mcqs, Pak Navy mcqs, CTS mcqs, ETEA mcqs and others. The most occurred mcqs of D.C Motors in past papers. Past papers of D.C Motors mcqs. Past papers of D.C Motors MCQs. D.C Motors Mcqs are the necessary part of any competitive / job related exams. The D.C Motors mcqs having specific numbers in any written test. It is therefore everyone have to learn / remember the related D.C Motors mcqs. The Important series of D.C Motors Mcqs are given below:
No-load speed of which of the following motor will be highest ?
A. Cumulative compound motor
B. Series motor
C. Shunt motor
D. Differentiate compound motor
The direction of rotation of a D.C. series motor can be changed by___________?
A. interchanging supply terminals
B. interchanging field terminals
C. either of Above
D. None of the above
Which of the following application requires high starting torque ?
A. Centrifugal pump
B. Lathe machine
C. Locomotive
D. Air blower
If a D.C. motor is to be selected for conveyors, which rriotor would be preferred ?
A. Series motor
B. Differentially compound motor
C. Shunt motor
D. Cumulative compound motor
Which D.C. motor will be preferred for machine tools ?
A. Cumulative compound motor
B. Shunt motor
C. Series motor
D. Differential compound motor
Differentially compound D.C. motors can find applications requiring___________?
A. variable speed
B. low starting torque
C. high starting torque
D. frequent on-off cycles
Which D.C. motor is preferred for elevators ?
A. Series motor
B. Shunt motor
C. Differential compound motor
D. Cumulative compound motor
According to Fleming’s left-hand rule, when the forefinger points in the direction of the field or flux, the middle finger will point in the direction of_________________?
A. current in the conductor aovtaat of conductor
B. resultant force on conductor
C. Resistence In Conductor
D. none of the above
If the field of a D.C. shunt motor gets opened while motor is running______________?
A. the armature current will reduce
B. the speed of motor will be reduced %
C. the motor will attain dangerously high speed 1
D. the motor will continue to nuvat constant speed
Starters are used with D.C. motors because______________?
A. these motors are not self-starting
B. these motors have high starting torque
C. back e.m.f. of these motors is zero initially
D. to restrict armature current as there is no back e.m.f. while starting
In D.C. shunt motors as load is reduced__________________?
A. the speed will reduce
B. the speed will increase in proportion to reduction in load
C. the speed will remain almost/constant
D. the speed will increase abruptly
A D.C. series motor is that which______________?
A. has its field winding consisting of thick wire and less turns
B. can be started easily without load
C. has a poor torque
D. has almost constant speed
For starting a D.C. motor a starter is required because___________?
A. it starts the motor
B. it limits the starting current to a safe value
C. it limits the speed of the motor
D. none of the above
The type of D.C. motor used for shears and punches is_____________?
A. series motor
B. shunt motor
C. differential compoutid D.C. motor
D. cumulative compound D.C. motor
If a D.C. motor is connected across the A.C. supply it will_______________?
A. not run
B. run at normal speed
C. run at lower speed
D. burn due to heat produced in the field winding by .eddy currents
To get the speed of D.C, motor below the normal without wastage of electrical energy is used?
A. Ward Leonard control
B. any of the above method
C. rheostatic control
D. none of the above method
When two D.C. series motors are connected in parallel, the resultant speed is____________?
A. loss than the normal speed
B. more than the normal speed
C. normal speed
D. zero
The speed of a D.C. shunt motor more than its full-load speed can be obtained by_____________?
A. decreasing the field current
B. decreasing the armature current
C. increasing the field current
D. increasing the armature current
In a D.C. shunt motor, speed is______________?
A. independent of armature current
B. proportional to the square of the current
C. directly proportional to the armature current
D. inversely proportional to the armature current
A direct on line starter is used: for starting motors___________?
A. up to 5 H.P
B. up to 15 H.P
C. up to 10 H.P
D. up to 20 H.P
What will happen if the back e.m.f. of a D.C. motor vanishes suddenly?
A. The motor will continue to run
B. The motor will stop
C. The armature may burn
D. The motor will run noisy
In case of D.C. shunt motors the speed is dependent on back e.m.f. only because____________?
A. armature drop is negligible
B. back e.m.f. is equal to armature drop
C. flux is proportional to armature current
D. flux is practically constant in D:C. shunt motors
In a D.C. shunt motor, under the conditions of maximum power, the current in the armature will be_____________?
A. rated full-load current
B. almost negligible
C. less than full-load current
D. more than full-load current
These days D.C. motors are widely used in____________?
A. air compressors
B. pumping sets
C. electric traction
D. machine shops
By looking at which part of the motor, it can be easily confirmed that a particular motor is D.C. motor?
A. Shaft
B. Frame
C. Commutator
D. Stator
In which of the following applications D.C. series motor is invariably tried?
A. Starter for a car
B. Fan motor
C. Drive for a water pump
D. Motor operation in A.C. or D.C
In D.C. machines fractional pitch winding is used__________?
A. to reduce copper losses
B. to improve cooling
C. to increase the generated e.m.f.
D. to reduce the sparking
A three point starter is considered suitable for______________?
A. shunt, compound and series motors
B. shunt as well as compound motors
C. shunt motors
D. all D.C. motors
In case-the conditions for maximum power for a D.C. motor are established, the efficiency of the motor will be______________?
A. around 90%
B. 100%
C. anywhere between 75% and 90%
D. less than 50%
The ratio of starting torque to full-load torque is least in case of____________?
A. compound motors
B. shunt motors
C. series motors
D. none of the above
In D.C. motor which of the following can sustain the maximum temperature rise?
A. Commutator
B. Slip rings
C. Field winding
D. Armature winding
Which of the following law/rule can he used to determine the direction of rotation of D.C. motor ?
A. Faraday’s law
B. Lenz’s law
C. Coloumb’s law
D. Fleming’s left-hand rule
Which of the following load normally needs starting torque more than the rated torque?
A. Air compressors
B. Conveyors
C. Blowers
D. Centrifugal pumps
The starting resistance of a D.C. motor is generally_______________?
A. low
B. 1000 Q
C. around 500 Q
D. infinitely large
The speed of a D.C. series motor is_____________?
A. proportional to field current
B. proportional to the square of the armature current
C. proportional to the armature current
D. inversely proportional to the armature current
In a D.C. series motor, if the armature current is reduced by 50%, the torque of the motor will be equal to
A. 50% of the previous value
B. 100% of the previous value
C. 25% of the previous value
D. 10% of the previous value
E. none of the above
The current drawn by the armature of D.C. motor is directly proportional to__________?
A. the torque required
B. the voltage across the terminals
C. the speed of the motor
D. none of the above
The power mentioned on the name plate of an electric motor indicates____________?
A. the power drawn in kVA
B. the power drawn in kW
C. the gross power
D. the output power available at the shaft
Which D.C. motor has got maximum self loading property?
A. Shunt motor
B. Series motor
C. Cumulatively compounded ‘motor
D. Differentially compounded motor
Which D.C. motor will be suitable along with flywheel for intermittent light and heavy loads?
A. Shunt motor
B. Series motor
C. Cumulatively compounded motor
D. Differentially compounded motor
If a D.C. shunt motor is working at no load and if shunt field circuit suddenly opens__________?
A. this will make armature to take heavy current, possibly burning it
B. nothing will happen to the motor
C. this will result in excessive speed, possibly destroying armature due to excessive centrifugal stresses D. motor will run at very slow speed
D.C. series motors are used______________?
A. where load changes frequently
B. where load is constant
C. where constant operating speed is needed
D. in none of the above situations
For the same H.P. rating and full load speed, following motor has poor starting torque_____________?
A. series
B. shunt
C. differentially compounded
D. cumulativelyc’ompounded
In case of conductively compensated D.C. series motors, the compensating winding is provided______________?
A. in parallel with armature winding
B. as separately wound unit
C. in series with armature winding
D. in parallel with field winding
Which of the following motor is preferred for operation in highly explosive atmosphere ?
A. Shunt motor
B. Series motor
C. Air motor
D. Battery operated motor
If the supply voltage for a D.C. motor is increased, which of the following will decrease ?
A. Operating speed
B. Starting torque
C. Full-load current
D. All of the above
Which one of the following is not the function of pole shoes in a D.C. machine ?
A. To reduce eddy current loss
B. To spread out flux for better uniformity
C. To support the field coils
D. To reduce the reluctance of the magnetic path
The mechanical power developed by a shunt motor will be maximum when the ratio of back e.m.f. to applied voltage is______________?
A. 2.0
B. 4.0
C. 1.0
D. 0.5
The condition for maximum power in case of D.C. motor is______________?
A. supply voltage = | x back e.m.f
B. back e.m.f. = | x supply voltage
C. back e.m.f. = 2 x supply voltage
D. supply voltage = back e.m.f
For which of the following applications a D.C. motor is preferred over an A.C. motor ?
A. High speed operation
B. Low speed operation
C. Variable speed operation
D. Fixed speed operation
In D.C. machines the residual magnetism is of the order of_________________?
A. 2 to 3 per cent
B. 20 to 25 per cent
C. 10 to 15 per cent
D. 50 to 75 per cent
Which D.C. motor is generally preferred for cranes and hoists ?
A. Series motor
B. Cumulatively compounded motor
C. Shunt motor
D. Differentially compounded motor
Three point starter can be used for______________?
A. shunt motor only
B. series motor only
C. compound motor only
D. both shunt and compound motor
Sparking, is discouraged in a D.C. motor because_____________?
A. it increases the input power con-sumption
B. commutator gets damaged
C. both
D. none of the above
Speed control by Ward Leonard method gives uniform speed variation_____________?
A. in one direction
B. in both directions
C. above normal speed only
D. below normal speed only
Flywheel is used with D.C. compound motor to reduce the peak demand by the motor, compound motor will have to be_____________?
A. under compounded
B. level compounded
C. cumulatively compounded
D. differentially compounded
Following motor is used where high starting torque and wide speed range control is required?
A. Single phase capacitor start
B. Induction motor
C. Synchronous motor
D. D.C. motor
E. None of the above
In a differentially compounded D.C. motor, if shunt field suddenly opens____________?
A. the motor will first stop and then run in opposite direction as series motor
B. the motor will work as series motor and run at high speed in the same direction
C. the motor will work as series motor and run at slow speed in the same direction
D. the motor will not work and come to stop
Buses, trains, trolleys, hoists, cranes require high starting torque and therefore make use of_____________?
A. D.C. series motor
B. induction motor
C. D.C. shunt motor
D. all of above motors
Which of the following motor has the poorest speed regulation ?
A. Differential compound motor
B. Series motor
C. Shunt motor
D. Cumulative compound motor
As -the load is increased the speed of D.C. shunt motor will____________?
A. reduce slightly
B. increase proportionately
C. increase slightly
D. remains unchanged
The armature torque of the D.C. shunt motor is proportional to____________?
A. field flux only
B. armature current only
C. both
D. none of the above
Which of the following method of speed control of D.C. machine will offer minimum efficiency ?
A. Field control method
B. Voltage control method
C. Armature control method
D. All above methods
Usually wide and sensitive speed control is desired in case of____________?
A. elevators
B. centrifugal pumps
C. steel rolling mills
D. colliery winders
The speed of a motor falls from 1100 r.p.m. at no-load to 1050 r.p.m. at rated load. The speed regulation of the motor is______________?
A. 6.77%
B. 4.76%
C. 2.36%
D. 8.84%
The armature voltage control of D.C. motor provides____________?
A. constant torque drive
B. constant current drive
C. constant voltage drive
D. none of the above
As there is no back e.m.f. at the instant of starting a D.C. motor, in order to prevent a heavy current from flowing though the armature circuit____________________?
A. a resistance is connected in series with armature
B. armature is temporarily open circuited
C. a resistance is connected parallel to the armature
D. a high value resistor is connected across the field winding