Departmental (other) • 2024 • Engineering Paper-II (Mechanical Engineer Under Electrical Wing)
A centrifugal compressor works on the principle of-
A)
Conversion of pressure energy into kinetic energy
B)
Conversion of kinetic energy into pressure energy
C)
Centripetal action
D)
Generating pressure directly
Option B is correct: Conversion of kinetic energy into pressure energy.
Departmental (other) • 2024 • Engineering Paper-II (Mechanical Engineer Under Electrical Wing)
A turbine pump is basically a centrifugal pump equipped additionally with-
A)
adjustable blades
B)
backward curved blades
C)
vaned diffusion casing
D)
inlet guide blades
Option D is correct: inlet guide blades.
Departmental (other) • 2024 • Engineering Paper-II (Mechanical Engineer Under Electrical Wing)
Draft tube at the exit of a Reaction turbine used for hydroelectric project is-
A)
above or below the water surface, depends on unit speed of the turbine
B)
always above the water surface
C)
always immersed in water
D)
may either be below or above the water surface
Option C is correct: always immersed in water.
Departmental (other) • 2024 • Engineering Paper-II (Mechanical Engineer Under Electrical Wing)
The pressure ratio in gas turbines is of the order of-
A)
2:1
B)
4:1
C)
6:1
D)
12:1
Option C is correct: 6:1.
Departmental (other) • 2024 • Engineering Paper-II (Mechanical Engineer Under Electrical Wing)
Cavitation in hydraulic turbine results in-
A)
Noise and vibration
B)
reduction and discharge
C)
drop in output and efficiency
D)
rough surfaces
Option C is correct: drop in output and efficiency.
Departmental (other) • 2024 • Engineering Paper-II (Mechanical Engineer Under Electrical Wing)
For non-parallel non-intersecting shafts, power can be transmitted with the help of-
A)
Pair of helical gear
B)
Pair of spur gear
C)
Pair of spiral gear
D)
Oldham coupling
Option A is correct: Pair of helical gear.
Departmental (other) • 2024 • Engineering Paper-II (Mechanical Engineer Under Electrical Wing)
Governing mechanism used in case of Francis and Kaplan turbines is-
A)
Guide vane
B)
Nozzle needle
C)
Control valve
D)
Dam gates
Option A is correct: Guide vane.
Departmental (other) • 2024 • Engineering Paper-II (Mechanical Engineer Under Electrical Wing)
Too low welding current in arc welding would result in-
A)
excessive piling up of weld metal, poor penetration, wasted electrodes
B)
excessive spatter, under cutting along edges, irregular deposits, wasted Electrodes
C)
too small bead, weak weld and wasted electrodes
D)
excessive piling up of weld metal, overlapping, without penetration of edges, wasted electrodes
Option C is correct: too small bead, weak weld and wasted electrodes.
Departmental (other) • 2024 • Engineering Paper-II (Mechanical Engineer Under Electrical Wing)
In centrifugal pumps, maximum efficiency is obtained when the blades are-
A)
Straight
B)
bent forward
C)
bent backward
D)
radial
Option C is correct: bent backward.
Departmental (other) • 2024 • Engineering Paper-II (Mechanical Engineer Under Electrical Wing)
The specific speed of a centrifugal pump is given by-
A)
NVQ / H
B)
NVQ / H^3
C)
NVQ / H^3 (approx based on text)
D)
He
Option C is correct: NVQ / H^3 (approx based on text).
Departmental (other) • 2024 • Engineering Paper-II (Mechanical Engineer Under Electrical Wing)
Which is the desirable physical property of a refrigerant?
A)
Toxic
B)
Explosive
C)
Low boiling point
D)
High freezing point
Option C is correct: Low boiling point.
Departmental (other) • 2024 • Engineering Paper-II
The speed at which a 6-pole alternator should be driven to generate 50 cycles per second is
A)
1500 rp.m
B)
1000 rp.m
C)
800rp.m
D)
500rp.m
Option A is correct: 1500 rp.m.
Departmental (other) • 2024 • Engineering Paper-II
A 3-phase load is balanced if all three phases have the same
A)
impedance
B)
power factor
C)
impedance and power factor
D)
none of the above
Option C is correct: impedance and power factor.
Departmental (other) • 2024 • Engineering Paper-II
Inductive reactance is measured in ohms because it
A)
reduces the amplitude of the alternating current
B)
increases the amplitude of alternating current
C)
increases the amplitude of direct current
D)
has a back e.m.f opposing a steady direct current
Option A is correct: reduces the amplitude of the alternating current.
Departmental (other) • 2024 • Engineering Paper-II
Reactive power in an a.c circuit is
A)
measured by a wattmeter
B)
the useful power
C)
consumed in the circuit
D)
a liability on the circuit
Option D is correct: a liability on the circuit.
Departmental (other) • 2024 • Engineering Paper-II
The power factor of an a.c. circuit is given by
A)
X/R
B)
Z/R
C)
RX
D)
R/Z
Option D is correct: R/Z.
Departmental (other) • 2024 • Engineering Paper-II
A low power factor of the circuit means that it will
A)
draw more active power
B)
draw less line current
C)
draw more reactive power
D)
cause less voltage drop in the line
Option C is correct: draw more reactive power.
Departmental (other) • 2024 • Engineering Paper-II
In a capacitor the electric charge is stored in
A)
dielectric
B)
metal plates
C)
both dielectric and metal plates
D)
electric charge is not stored
Option B is correct: metal plates.
Departmental (other) • 2024 • Engineering Paper-II
The phase sequence of a 3-phase balanced system is RYB. The other possible phase sequence can be
A)
BRY
B)
YRB
C)
RBY
D)
BRB
Option A is correct: BRY.
Departmental (other) • 2024 • Engineering Paper-II
Lenz’s law is related to
A)
the direction of magnetic field
B)
the direction of motion of conductor
C)
the direction of the induced current
D)
both (a) and (b)
Option C is correct: the direction of the induced current.
Departmental (other) • 2024 • Engineering Paper-II
Mesh current analysis is based on
A)
Kirchhoff’s current law
B)
Kirchhoff’s voltage law
C)
Maxwell’s law
D)
Norton’s law
Option B is correct: Kirchhoff’s voltage law.
Departmental (other) • 2024 • Engineering Paper-II
If RL of Figure is the load resistance, then Thevenin’s equivalent resistance Rth of the circuit will be
A)
3Ω
B)
5Ω
C)
7Ω
D)
10Ω
Option A is correct: 3Ω.
Departmental (other) • 2024 • Engineering Paper-II
When magnetic flux linking a conductor changes
A)
an e.m.f is always induced
B)
a current is always induced
C)
both e.m.f and current are always induced
D)
neither e.m.f nor current are induced
Option A is correct: an e.m.f is always induced.
Departmental (other) • 2024 • Engineering Paper-II
The heat produced (in keals) in a resistance R ohms when a current I amperes flows through it for t seconds is given by
A)
I²Rt
B)
I²Rt/(4.2x10³)
C)
I²Rt x 4.2
D)
IRt/J
Option B is correct: I²Rt/(4.2x10³).
Departmental (other) • 2024 • Engineering Paper-II
The most widely used rectifier circuit is
A)
half-wave rectifier
B)
centre-tap circuit
C)
bridge circuit
D)
full-wave rectifier
Option C is correct: bridge circuit.
