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WorksheetsDC MOTOR
Total questions: 20
Worksheet time: 10mins
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
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
Which factors not
affecting the speed of dc motors?
Flux
Current
Applied voltage.
Voltage across the armature
How do u obtain desired speed of an armature controlled DC motor ?
by varying armature current
by varying the armature voltage
by varying emf
by varying transformer voltage
A coil carries a current in a magnetic field. The coil experiences a turning effect.
Which device uses this effect?
a DC motor
an electromagnet
a relay
a transformer
The part of an electric motor that doesn't spin is called the...
armature
commutator
stator
bearings
In the image shown, the dark grey shapes are called:
Brushes
Armatures
Commutators
Windings
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
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
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
Operating principle of DC motor formula.
F=V/R
F=VR
F=IV
F=BiL
Which of the following is not the method of electrical braking?
Plugging or counter-current
Dynamic or rheostatic
Regenerative
Eddy current
Plugging is applied in a motor, if we don’t make the switch OFF what will happen?
Motor will come to rest as a result of plugging
Motor will come to rest and will start rotating in another direction
Motor will burn
Nothing will happen
In which of the following electrical braking method, energy is supplied back to the supply?
Plugging
Dynamic braking
Regenerative braking
In all electrical braking
