MES Departmental • 2023 • Paper-II
In a transistor with normal bias
A)
the emitter junction has a low resistance
B)
the emitter junction is reversed biased
C)
the emitter junction offers high resistance
D)
none of the above
Option A is correct: the emitter junction has a low resistance.
MES Departmental • 2023 • Paper-II
The value of capacitive reactance increases as the
A)
value of capacitance increases
B)
frequency decreases
C)
voltage increases
D)
current increases
Option B is correct: frequency decreases.
MES Departmental • 2023 • Paper-II
Inductive reactance is measured in ohms because it
A)
reduces the amplitude of 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 D is correct: has a back e.m.f. opposing a steady direct current.
MES Departmental • 2023 • Paper-II
The time period of a direct current is
A)
infinite
B)
zero
C)
finite
D)
random
Option A is correct: infinite.
MES Departmental • 2023 • Paper-II
If e1 = Asinwt and e2 = B sin (wt-f), then
A)
e1 lags e2 by f
B)
e2 lags e1 by f
C)
e1 is in phase with e2
D)
e2 is in phase with e1
Option B is correct: e2 lags e1 by f.
MES Departmental • 2023 • Paper-II
The speed at which a 6-pole alternator should be driven to generate 50 cycles per second is
A)
1500 r.p.m
B)
1000 r.p.m
C)
800 r.p.m
D)
500 r.p.m
Option A is correct: 1500 r.p.m.
MES Departmental • 2023 • Paper-II
The advantage of star-connected supply system is that
A)
line current is equal to phase current
B)
two voltages can be used
C)
phase sequence can easily be changed
D)
it is a simple arrangement
Option B is correct: two voltages can be used.
MES Departmental • 2023 • Paper-II
Lenz’s law is related to
A)
thedirection of magnetic field
B)
thedirection 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.
MES Departmental • 2023 • Paper-II
In an R-L series circuit, line current
A)
leads the applied voltage
B)
lags behind the applied voltage
C)
is in phase with the applied voltage
D)
none of the above
Option B is correct: lags behind the applied voltage.
MES Departmental • 2023 • Paper-II
When 3-phase system is balanced, the neutral wire carries
A)
no current
B)
one-third of current for each phase
C)
half of current for each phase
D)
one-fourth of current for each phase
Option A is correct: no current.
MES Departmental • 2023 • Paper-II
Corona effect can be reduced by
A)
increasing conductor size
B)
decreasing conductor size
C)
decreasing conductor spacing
D)
none of the above
Option A is correct: increasing conductor size.
MES Departmental • 2023 • Paper-II
When the speed of an alternator is reduced by half, the generator e.m.f will become
A)
twice
B)
one-fourth
C)
half
D)
four times
Option C is correct: half.
MES Departmental • 2023 • Paper-II
The unit of capacitance is
A)
Farad
B)
Farad/m
C)
Farad/m2
D)
Farad/m3
Option A is correct: Farad.
MES Departmental • 2023 • Paper-II
According to Faraday’s Laws of Electromagnetic Induction, an e.m.f. is induced in a conductor whenever it
A)
lies in a magnetic field
B)
cuts magnetic field
C)
moves parallel to the direction of the magnetic field
D)
lies perpendicular to the magnetic flux
Option B is correct: cuts magnetic field.
MES Departmental • 2023 • Paper-II
Total minimum number of discs in a string of porcelain insulators for 132kV AC overhead transmission line is
A)
5
B)
6
C)
7
D)
8
Option D is correct: 8.
MES Departmental • 2023 • Paper-II
A thyristor can be brought to forward conducting state with gate-circuit open when the applied voltage exceeds
A)
the forward break-over voltage
B)
reverse breakdown voltage
C)
1.5V
D)
2.0 V
Option A is correct: the forward break-over voltage.
