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WorksheetsEE-II-UNIT- 5 - DC MOTOR
Total questions: 60
Worksheet time: 30mins
WHICH PROVIDES MECHANICAL POWER TO DC MACHINES?
STATOR
ROTOR
YOKE
WHICH TYPE OF DC MOTOR CAN GIVE HIGH STARTING TORQUE
SERIES WOUND
SHUNT WOUND
LONG SHUNT
WHICH TYPE OF DC MOTOR IS USED FOR TRACTION WORK
SERIES WOUND
SHUNT WOUND
COMPOUND
COMBINATION OF SERIES AND SHUNT WOUND DC MOTOR IS ----------
SERIES WOUND DC MOTOR
SHUNT WOUND DC MOTOR
COMPOUND WOUND TYPE DC MOTOR
WHICH TYPE OF DC MOTOR IS USED IN BLOWER?
SERIES WOUND
SHUNT WOUND
SHORT SHUNT
COMPOUND MOTOR IS USED IN -------- APPLICATION
TRACTION WORK
PRINTING PRESS
BLOWER
WHICH TYPE OF DC MOTOR HAS MEDIUM STARTING TORQUE?
SERIES WOUND
SHUNT WOUND
COMPOUND TYPE
BRUSHES ARE MADE UP OF -----------------
CARBON OR GRAPHITE
GERMANIUM OR SILICON
SILICON STELL OR IRON
WHAT IS THE ANOTHER NAME FOR COMMUTATOR?
SLIP RING
SPLIT RING OR HALF RING
BRUSHES
WHICH IS MOVING PART IN DC MOTOR
STATOR
ROTOR
YOKE
DC MOTOR CONVERTS ------- ENERGY INTO ----------ENERGY
MECHANICAL, ELECTRICAL
ELECTRICAL, MECHANICAL
KINETIC, POTENTIAL
THE WORKING PRINCIPLE OF DC MOTOR IS---------
MUTUAL INDUCTION
FLEMING'S RIGHT HAND
LORENTZ LAW
WHICH DEVICE IS CONSTRUCTION-WISE THE SAME AS DC MOTOR?
DC GENERATOR
TRANSFORMER
INDUCTOR
AS PER FLEMING'S LEFT-HAND RULE THUMB FINGER SHOWS THE
DIRECTION OF MAGNETIC FIELD
DIRECTION OF CURRENT
DIRECTION OF FORCE
AS PER FLEMING'S LEFT-HAND RULE INDEX FINGER SHOWS THE
DIRECTION OF FORCE
DIRECTION OF MAGNETIC FIELD
DIRECTION OF CURRENT
AS PER FLEMING'S LEFT-HAND RULE MIDDLE FINGER SHOWS THE---------
DIRECTION OF FORCE
DIRECTION OF MAGNETIC FIELD
DIRECTION OF CURRENT
WHAT IS TORQUE?
TWISTING FORCE
KINETIC FORCE
MAGNETIC FORCE
WHAT IS BACK EMF?
THE VOLTAGE OPPOSES THE SUPPLY VOLTAGE
THE VOLTAGE DOES NOT OPPOSE THE SUPPLY VOLTAGE
SUPPLY VOLTAGE
BACK EMF OF DC MOTOR IS----------
Eb = PΦNZ / 60A
EB = PΦN / 60AZ
EB = PΦZ / 120AN
GENERATOR CONVERTS ------ ENERGY INTO ----- ENERGY
MECHANICAL, ELECTRICAL
ELECTRICAL, MECHANICAL
POTENTIAL,KINETIC
The PWM control of DC motor varies _________
a) linearly with speed
b) inversely with speed
c) parabolically with speed
d) exponentially with speed
Mark the wrong option. Which of the following cause and effect behaviour in speed control is correct when field resistance is increased.
a) Decrease in flux
b) Increase in armature current
c) Increase in EMF
d) Decrease in speed
At a very low speed, increase in field resistance will _________
a) decrease the speed of motor
b) increase the speed of motor
c) not have signicant effect on speed
d) no effect
Small DC motors have best speed control by _________
a) armature voltage control
b) field resistance control
c) any of the methods
d) none of the mentioned
To implement armature voltage control, it must be ensured that _________
a) it is used on separately excited machine
b) it is used on shunt machine
c) it is used on series machine
d) any of the mentioned machine
Armature voltage control works for speeds _____ base speed and field resistance control works well for speed _____ base speed.
a) below, above
b) above, below
c) above, above
d) below, below
Speed of d.c. shunt motors are controlled by
a. Flux control method
b. Rheostatic control method
c. Voltage control method
d. All of these
With the increase in temperature, the speed of series and shunt motor will
a. Increase, decrease
b. Decrease, increase
c. Increase, increase
d. Decrease, decrease
In the flux control method for controlling the speed of d.c. shunt motor, the speed control is not possible
a. Below normal rated speed
b. Above normal rated speed
c. Both (a) and (b)
d. None of these
If a resistance is added in series with the field winding of d.c. shunt motor, then its
a. Both speed and torque decreases
b. Both speed and torque increases
c. Speed decreases, torque increases
d. Speed increases, torque decreases
In a DC Motor, the coil of the rotor turns into an electromagnet when
the rotor rotates inside the stator
electricity (current) flows through the coil
the rotor is turned by the axle
the it sits int the field of the stator
The rotor is the name of the part that is
the rotating coil inside the stator's field
the stationary magnets around the rotating coil
the spring loaded parts that contact the commutator
the split ring that carries electricity to the coil
The stator is
the sets of coiled wires that create the armature
the split ring that carries electricity to the rotor
the spring loaded connections that touch the commutator while it rotates to carry current
the magnets surrounding the rotor that create the magnetic field that the coil is attracted and repelled by causing motion.
An electromagnet can be made with a coil of wire around a nail if
the wire is magnetized by a compass
the wire has a current running through it
the wire is touching 2 magnet
the nail is touching a battery on the anode
Which part may perhaps wear out the fastest in the motor?
The brushes because they are always sliding against the commutator
the coils because the electric current makes them weak
the stator because it is always moving
the rotor because the stator pulls and pushes it too hard
WHICH PROVIDES MECHANICAL POWER TO DC MACHINES?
STATOR
ROTOR
YOKE
WHICH TYPE OF DC MOTOR CAN GIVE HIGH STARTING TORQUE
SERIES WOUND
SHUNT WOUND
LONG SHUNT
WHICH TYPE OF DC MOTOR IS USED FOR TRACTION WORK
SERIES WOUND
SHUNT WOUND
COMPOUND
COMBINATION OF SERIES AND SHUNT WOUND DC MOTOR IS ----------
SERIES WOUND DC MOTOR
SHUNT WOUND DC MOTOR
COMPOUND WOUND TYPE DC MOTOR
WHICH TYPE OF DC MOTOR IS USED IN BLOWER?
SERIES WOUND
SHUNT WOUND
SHORT SHUNT
COMPOUND MOTOR IS USED IN -------- APPLICATION
TRACTION WORK
PRINTING PRESS
BLOWER
WHICH TYPE OF DC MOTOR HAS MEDIUM STARTING TORQUE?
SERIES WOUND
SHUNT WOUND
COMPOUND TYPE
BRUSHES ARE MADE UP OF -----------------
CARBON OR GRAPHITE
GERMANIUM OR SILICON
SILICON STELL OR IRON
BRUSHES ARE MADE UP OF -----------------
CARBON OR GRAPHITE
GERMANIUM OR SILICON
SILICON STELL OR IRON
WHAT IS THE ANOTHER NAME FOR COMMUTATOR?
SLIP RING
SPLIT RING OR HALF RING
BRUSHES
WHICH IS MOVING PART IN DC MOTOR
STATOR
ROTOR
YOKE
What does the thumb indicate in flemings left hand rule?
Force
Motion
Current
Magnetic field direction
Which rule can be used to work out which way a coil of wire rotates in a motor?
Fleming's left-hand rule
Fleming's right-hand rule
Give two ways you can reverse the direction of a basic dc motor?
Reverse the current
Keep the current the same
Reverse the magnetic field
Keep the magnetic field the same
How does a split ring commutator work?
Swaps the contact evert full turn, so that the left-hand and right-hand arms of the coil always experience a force in the same direction.
Swaps the contact evert half turn, so that the left-hand and right-hand arms of the coil do not experience a force in the same direction.
Swaps the contact evert half turn, so that the left-hand and right-hand arms of the coil always experience a force in the same direction.
Which of the following is the best braking method?
a) Friction
b) Electromechanical action
c) Eddy-currents
d) Electric braking
DC motor is still widely used in tractions due to its excellent braking properties.
a) True
b) False
Which of the following is not the method of electrical braking?
a) Plugging or counter-current
b) Dynamic or rheostatic
c) Regenerative
d) Eddy current
Which of the following is the plugging method of braking?
a) Reversal of field connections
b) Reversal of armature connections
c) Addition of equal and opposite field
d) Removal of field circuit from current machine circuit
Plugging is applied in a motor, if we don’t make the switch OFF what will happen?
a) Motor will come to rest as a result of plugging
b) Motor will come to rest and will start rotating in another direction
c) Motor will burn
d) Nothing will happen
Plugging is used in ____________
a) Small motors only
b) Small and medium powered
c) Only in large heavy machines
d) Everywhere
Which of the following is dynamic braking?
a) Reversal of field connections
b) Reversal of armature connections
c) Addition of equal and opposite field
d) Removal of armature circuit from current machine circuit
In dynamic braking, when braking is applied system acts as ___________
a) Freely running machine
b) Motor with slow speed
c) Generator
d) Motor with same speed in opposite direction
In which of the following electrical braking method, energy is supplied back to the supply?
a) Plugging
b) Dynamic braking
c) Regenerative braking
d) In all electrical braking
Braking time in the dynamic braking is the function of _____________
a) System inertia
b) Load torque
c) Motor rating
d) All- system inertia, load torque and motor rating
