# Basic Electrical Engineering Expected MCQ PDF 3 For Coal India Limited (CIL) MT Exam 2017

1)   In case of a synchronous generator, armature winding and field winding are

a. Both stationary
b. Stationary, rotating
c. Rotating, stationary
d. Both rotating

2)   Salient pole type motors have

a. Large diameter and large axial length
b. Small diameter and small axial length
c. Large diameter and small axial length
d. Small diameter and large axial length

 ANSWER: Large diameter and small axial length

3)   Short pitched windings are mainly used because it

a. Gives better waveform of the generated emf
b. Eddy current and hysteresis losses are reduced
c. Less copper is used
d. All of these

4)   The number of conductors in synchronous generators is equal to

a. The number of turns per phase
b. Twice the number of coils per phase
c. Half of the number of coils per phase
d. None of these

 ANSWER: Twice the number of coils per phase

5)   If Kf, Kc and Kd
are the coefficient of form factor, pitch factor and distribution
factor respectively then the rms value of induced emf per phase is given
by

a. KfKcKd f ∅T
b. 1.414KfKcKd f ∅T
c. 4KfKcKd f ∅T
d. 1.11KfKcKd f ∅T

6)   The steel used for laminations should have

a. High permeability and high hysteresis
b. High permeability and low hysteresis
c. Low permeability and hysteresis
d. Low permeability and high hysteresis

 ANSWER: High permeability and low hysteresis

7)   In core type
transformer, the coils are wound in helical layers, each layers being
insulated from each other by using

a. Paper
b. Cloth
c. Cooling ducts
d. All of these

8)   In transformer if the secondary is open circuited then its terminal voltage is

a. Same as the induced emf
b. Greater than the induced emf
c. Lesser than the induced emf
d. None of these

 ANSWER: Same as the induced emf

9)   If ∅m is the maximum value of flux in the core then the average rate of change of flux is

a. f∅m
b. 2 f∅m
c. 4 f∅m
d. 4.44 f∅m

10)   If R1 is the primary winding resistance and R2 is the secondary winding resistance then the equivalent resistance of the transformer as referred to the primary is

a. R1+ R2/K2
b. R2+ R1/K2
c. R1+ K2R2
d. R2+ K2R1

11)   For induction motors,

a. Should be essentially a constant speed motor
b. Its speed reduces to some extent with increase in load
c. Does not need to be synchronized
d. All of these

12)   In induction motor, greater the number of poles

a. Lesser the speed
b. Greater the speed
c. Lesser the frequency
d. All of these

13)   The advantage of skewing in induction motor is / are

a. Motor runs smoothly as the magnetic hum is reduced
b. The tendency of the rotor teeth to remain under the stator teeth due to direct magnetic attraction is reduced
c. More uniform torque is obtained while running
d. All of these

14)   Slip ring induction motor are employed only for

a. Speed control
b. High starting torque
c. Both (a) and (b)
d. None of these

15)   The resultant flux in an induction motor is equal to the

a. Maximum value of flux due to any phase
b. Twice of the maximum value of flux due to any phase
c. 0.5 times the maximum value of flux due to any phase
d. 1.5 times the maximum value of flux due to any phase

 ANSWER: 1.5 times the maximum value of flux due to any phase

16)   Electrical energy can be converted into

a. Light energy
b. Electromagnetic energy
c. Electrochemical energy
d. All of these

17)   In a gas filled lamp, inert gases are filled in the lamp to

a. Compensate heat losses
b. Minimize the electricity use
c. Increase the brightness
d. None of these

18)   If the length of the filament is increased then the

a. Power also increases
b. Power decreases
c. Required oxygen increases
d. Flow of current increases

19)   The tube of a tube light is filled with

a. Fluorescent paste
b. Low pressure inert gas
c. Mercury
d. Only (b) and (c)

20)   Electric bell consists of a

a. Horse shoe type electromagnet
b. Circular electromagnet
c. Rod shaped electromagnet
d. All of these

21)   In cell, the current flows in outer circuit from

a. Positive terminal to negative terminal and electrons from negative terminal to positive terminal
b. Positive terminal to negative terminal and electrons from positive terminal to negative terminal
c. Negative terminal to positive terminal and electrons from negative terminal to positive terminal
d. Negative terminal to positive terminal and electrons from positive terminal to negative terminal

 ANSWER: Positive terminal to negative terminal and electrons from negative terminal to positive terminal

22)   Leclanche cell Daniel cell is an example of

a. both dry cell
b. both wet cell
c. dry cell, wet cell
d. wet cell, dry cell

23)   Secondary’s cells are

b. alkaline cell
c. both (a) and (b)
d. none of these

24)   In voltaic cell, anode and cathode of the cell is

a. copper electrode, zinc
b. zinc, copper
c. aluminium, zinc
d. nickel, cobalt

25)   In Daniel cell,

a. Layer of hydrogen bubbles is formed
b. Polarization takes place
c. Negative pole is a copper vessel
d. None of these

26)   For controlling the initial inrush current,

a. Reduced voltage is applied to the stator during the starting period
b. Reduced voltage is applied to the stator when the motor is running at rated speed
c. Either (a) or (b)
d. None of these

 ANSWER: Reduced voltage is applied to the stator during the starting period

27)   In India,
direct – on – line starter can be used for 3 – phase squirrel cage
induction motor up to the rating of

a. 5 HP
b. 10 HP
c. 15 HP
d. 25 HP

28)   Reduced voltage can be applied across the stator circuit by

a. Using an autotransformer
b. Connecting resistor in series with stator winding
c. Connecting inductor in series with stator winding
d. All of these

29)   If an
induction motor is initially connected in delta and then reconnected in
star then the current drawn will become

a. Thrice of the current drawn when connected in delta
b. Twice of the current drawn when connected in delta
c. One third of the current drawn when connected in delta
d. Half of the current drawn when connected in delta

 ANSWER: One third of the current drawn when connected in delta

30)   If an extra resistance is connected in the rotor circuit of slip ring induction motor, then

a. Starting current and torque decreases
b. Starting current increases and torque decreases
c. Starting current decreases and torque increases
d. Starting current and torque increases

 ANSWER: Starting current decreases and torque increases

31)   The atomic number of silicon and germanium is

a. 32, 14
b. 12, 19
c. 14, 32
d. 19, 12

32)   To move electrons from valence band to conduction band, the energy applied to the insulator is

a. Less than 15 eV
b. Equal to 15 eV
c. More than 15 eV
d. More than 25 eV

33)   Valence electrons of silicon and germanium are

a. 2, 4
b. 4, 4
c. 4, 2
d. 2, 2

34)   At low temperature, the semi conductor behaves as a

a. Perfect insulator
b. Perfect conductor
c. Perfect consulator
d. None of these

35)   If an external electric field is applied across the intrinsic semiconductor, then the

a. More number of electron holes pair combination will be broken
b. More number of electron holes pair combination will be evolved
c. Less number of electron holes pair combination will be broken
d. Less number of electron holes pair combination will be evolved

 ANSWER: More number of electron holes pair combination will be broken

36)   According to Kirchoff’s voltage law,

a. The algebraic sum of all the e.m.f’s in the circuit is zero
b. Algebraic sum all the voltage drops in the circuit is zero
c. Algebraic sum of e.m.f’s plus algebraic sum of voltage drops is equal to zero
d. All of these

 ANSWER: Algebraic sum of e.m.f’s plus algebraic sum of voltage drops is equal to zero

37)   Electrical work is

a. Directly proportional to the potential difference
b. Directly proportional to the charge
c. Directly proportional to the current
d. All of these

38)   If a current
of 5A flows through a resistor of 12 ohm then the power developed and
the energy dissipated in 2 minutes are

a. 300 W, 36000 J
b. 360 W, 30000 J
c. 380 W, 35000 J
d. 380 W, 36000 J

39)   The unit of electrical energy is / are

a. Joules
b. Watt – sec
c. Kilowatt – hour
d. All of these

40)   If a number of resistors are connected in parallel, then the reciprocal of total resistance is equal to

a. Sum of individual resistances
b. Sum of the reciprocal of individual resistances
c. Reciprocal of the sum of individual resistances
d. All of these

 ANSWER: Sum of the reciprocal of individual resistances

41)   Permeability of a material is

a. Directly proportional to both flux density and magnetizing force
b. Directly proportional to flux density and inversely proportional to the magnetizing force
c. Directly proportional to the magnetizing force and inversely proportional to the flux density
d. Inversely proportional to both flux density and magnetizing force

 ANSWER: Directly proportional to flux density and inversely proportional to the magnetizing force

42)   The amount of flux density set up in the core is dependent upon

a. Current
b. No. of turns, cross sectional area of core
c. Materials of the magnetic core, length of core
d. All of these

43)   When a solenoid attracts an iron bar,

a. They leave the south pole to go around to the north pole
b. They leave the north pole to go around to the south pole
c. They leave the north pole to go to infinity
d. They leave the south pole to go to the infinity

 ANSWER: They leave the north pole to go around to the south pole

44)   If two
conductors carrying currents in opposite direction are placed parallel
to each other then the magnetic field set up by the conductors

a. Attract each other
b. Repels each other
c. Perpendicular to each other
d. Parallel to each other

45)   According to
the End Rule, the current directions when looked from one end of the
coil if that end is South Pole and if the end is North Pole are

a. Both clockwise
b. Anticlockwise, clockwise
c. Clockwise, anticlockwise
d. Both anticlockwise

46)   When the
flux crosses the air gap, it bulges outward at the ends of the air gap
and the flux density in the air gap is reduced. This is known as

a. Leakage flux
b. Fringing
c. Relative permeability
d. Magnetizing force

47)   The induced emf sets up the direction of current in such a way that the magnetic field produced by it

a. Supports the cause producing it
b. Opposes the cause producing it
c. Increases
d. Decreases

 ANSWER: Opposes the cause producing it

48)   Which among the following sentences is correct?

a. Lenz’s law is used to find the direction of induced current
b. Fleming’s right hand rule is used to find the direction of induced current
c. Fleming’s left hand rule is used to find the direction of force
d. All of these

49)   If the magnetic field is stationary and the conductor is in motion then the emf induced is called

a. Dynamically induced emf
b. Statically induced emf
c. Self induced emf
d. Mutually induced emf