2018 FEBRUARY ELECTRICIAN THEORY SEMESTER-II PART-1


2018 FEBRUARY ELECTRICIAN THEORY SEMESTER-II PART-1

1. The EMF (Es) equation of the
 transformer in the secondary side is .....
a) E
ѕ= 4.44𝛟мf Nр Volt
b) Eѕ =  4.44𝛟мNѕ Volt Volt
c) Eѕ = 4.44𝛟 мf Nѕ Volt
d) Eѕ = 4.44 𝛟 мf Volt
Answer:- c) Eѕ = 4.44𝛟 мf Nѕ Volt

2. Buchholz's relay is connected in high
capacity power transformers. The purpose
of the Buchholz relay is to........
a) Arrest the flow of moisture into the tank
b) Disconnect the transformer,
    when dead short circuit fault occurs
c) Flow insulating oil from the
    conservator tank
d) Control the level of oil tank
Answer:- b) Disconnect the transformer,
    when dead short circuit fault occurs

3. A 5KVA, 400V/200V transformer
delivers a current of 25 Amps in secondary.
What is the current in primary side?
a) 50 Amps
b) 25 Amps
c) 17.5 Amps
d) 12.5 Amps
Answer:- d) 12.5 Amps

4. In full wave rectification, if the input
frequency is 50 Hz, then frequency
at the output of
filter is-
a) 50 Hz
b) 0 Hz
c) 100 Hz
d) 75 Hz
Answer:- b) 0 Hz

5. In a CE amplifier circuit the ac
    voltage between emitter and ground-
a) Is very high
b) May be high or low
c) Is zero
d) Depends upon circuit configuration
Answer:- c) Is zero

6. Which material is used for wiring
    continuous bus bar?
a) Aluminium
b) Copper
c) Both (A) and (B)
d) None of these
Answer:- a) Aluminium

7. When the coil moves at right angle to
the magnetic flux, the induced emf will be
a) Oscillating
b) Minimum
c) Zero
d) Maximum
Answer:- d) Maximum

8. Which among these is a method of wiring?
a) Joint box
b) Tee system
c) Loop in system
d) All of these
Answer:- d) All of these

9. The magnitude of the induced emf.
at zero degree angle is given by the formula
E = BLVsinθ
a) Induced voltage
b) Velocity of loop rotation
c) Value of the magnetic flux density
d) Velocity of the cutting force by
magnetic lines
Answer:- b) Velocity of loop rotation

10. The direction of rotation of do
shunt motor can be reversed by
interchanging-
a) The supply terminals
b) The field terminals
c) The armature terminals only
d) Either field or armature terminals
Answer:- d) Either field or armature
                  terminals


11. With the increase in the speed
       of a do motor-
a) Both back emf as well as line current
     increase
b) Both back emf and line current fall
c) Back emf increases but the line
    current falls
d) Back emf falls and line current
     increases
Answer:- c) Back emf increases but the line
                  current falls

12. According to the IS recommendation
the clearance between the bottom part
of the ceiling
fan and the floor should not be less than -
a) 1.3 m
b) 2.0m
c) 2.25 m
d) 2.40 m
Answer:- d) 2.40 m

13. Two pin sockets should not be
used in domestic wiring unless the
appliance to be
connected is -
a) Double earthed
b) Double insulated
c) Controlled by ELCB
d) Controlled by MCB
Answer:- b) Double insulated

14. D.C. shunt motors are commonly
used in-
a) Cranes
b) Electric traction
c) Elevators
d) Lathe machines
Answer:- d) Lathe machines

15. Size of the plate electrode used for
plate earthing should not be less than -
a) 12.5x12.5x0.12 cm
b) 20 x 20 x 0.25 cm
c) 30 x 30 x 0.28 cm
d) 60 x 60 x 0.315 cm
Answer:- d) 60 x 60 x 0.315 cm

16. In which principle, the earth resistance
tester does work?
a) Fall of resistivity method
b) Fall of potential method
c) Wheatstone bridge principle       
d) Fall of conductivity method
Answer:- b) Fall of potential method

17. What is the function of current reverses
which is used in earth resistance tester?
a) To convert AC voltage into DC voltage
b) To convert DC voltage into AC voltage
c) To reduce the vibration of the pointer
d) To reduce the effect of electrolytic emf
Answer:- d) To reduce the effect of electrolytic emf

18. You have to select a PF meter
suitable for connecting in a circuit for
PF measurements on what basis you will
select its range?
a) Suitability for the type of load
     (Inductive / capacitive/ Resistance)
b) PF range of meter (Lagging /
    Leading)Unity)
c) Voltage and current range of meter
    suitable to load
d) Current and PF range of meter
     matching to load
Answer:- c) Voltage and current range of meter
    suitable to load

19. Ammeters used for current
measurements in circuits with short
over load time, differs from other
application. Ammeter used in short
overload time circuit have -
a) Non-linear scale
b) Extended scale
c) Linear scale
d) Fine scale
Answer:- b) Extended scale

20. Instruments which must not be
used in the circuit when the power is
ON are -
a) Watt meter and PF meter
b) Frequency meter and Tong tester
c) Phase sequence meter and energy
    meter  
d) Ohmmeter and Megger
Answer:- d) Ohmmeter and Megger
21. Two types of multimeters are in use.
Analog type and Digital type. Chose the
correct statement applicable for both
the types. Both the meters -
a) Have moving elements, hence must
     be used in horizontal position
b) Can be used for current and voltage
     measurement without battery
c) Need manual zero setting for
     resistance measurement
d) Need battery for resistance
    measurements
Answer:- d) Need battery for resistance
    measurements

22. Power drawn by a welding shop
which has 3 phase, 415 V, 50Hz
 supply has to be measured. The
following loads are connected,
(a) 2 welding set of each 5KVA across
L1,L2 and 13. (b) One set of 5KVA
across L2 arid L3. What is the type of
wattmeter you
would choose for this measurement?
a) 3 element 3 wire type 3 phase
    wattmeter
b) One single phase wattmeter
     connected
between any two phase and multiply
 reading by three
c) 3 element 4 wire 3 phase watt meter
d) 2 element types 3 phase watt meter
Answer:- d) 2 element types 3 phase watt meter

23. D.C shunt motor is also called as-
a) Constant flux motor
b) Constant voltage motor
c) Variable voltage motor
d) Constant current motor
Answer:- a) Constant flux motor

24. To keep the continuity of serial
 lamp set circuit even across the fuse
bulb it is customaryto connect a
device across the each bulb as precaution.
What is the name of such device?
a) NTC thermistors
b) PTC thermistors
c) Voltage dependent resistor
d) Flasher
Answer:- a) NTC thermistors
25. The starter of a fluorescent tube
 has been removed from its holder
after the tubes is lighted. What will
happen to the function of the tube?
a) Tube will begin to flicker
b) Tube will go out immediately
c) Tube will operate normally
d) Tube will begin to hum very much
 Answer:- c) Tube will operate normally

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