Screening Test For The Selection of Assistant Professor (Contract)
In Electrical and Electronics Engineering
Government Engineering College Idukki
Question Paper and Answer Key
Correct choices are given in bold red colour letters.
GEC Idukki|EE|AP(Contract) Screening Test
Register Number:
Max. Marks: 160
Time: 1 hour.
1. A circuit as shown in Fig. 1 is used to charge a 24 V battery from a source voltage is
48 sin 314t. What is the duration for which the diode D1 conducts? Assume ideal diode.
Vm
R = 10Ω
supply voltage
is
D1
48 sin 314t
I
ωt
E = 24V
Fig. 1
A. 10 ms
Fig. 2
B. 6.67 ms
C. 0.382 s
D. 16.67 ms
2. The input current waveform (is ) of a converter is a square wave as shown in Figure 2, along
with the supply voltage (sinusoidal) waveform. What is the power factor at the input of the
converter?
A. 1.0
B. 0.9
C. 0.8
D. 0.707
3. In SCRs, the I 2 t rating is provided so as
A. to assess suitability in a power circuit.
B. to assess high-frequency switching capacity.
C. to help thermal design.
D. to design short circuit protection.
4. Identify the content of C register in microprocessor 8085, after executing the following segment of assembly language programme. The contents of memory locations:[0100]=00H;
[0101]=02H; [0200]=EE
LHLD 0100H
LXI B 0100H
XRA
ADD M
MOV E, M
XCHG
DCX B
XRA
A.
B.
C.
D.
00
FF
EE
Cannot be predicted
5. The number of poles of a sytem with characteristic equation s7 + 6s6 + 11s5 + 6s4 + s3 +
6s2 + 11s + 6 = 0 lie on the imaginary axis is:
A. 0
B. 2
21 May 2017
C. 4
D. 6
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Register Number:
0.5s + 1
is:
0.2s + 1
D. Depends on system transfer function.
6. The maximum phase lead produced by a phase lead compensator Gc (s) =
A. 68.2o
B. 21.8o
C. 25.4o
7. Identify the nature of function V (x1 , x2 ) = 21 x21 + 12 x22 + x1 x2 .
A. Postive Definite
B. Positive Semidefinite
C. Negative definite
D. Indefinite
8. In the circuit shown in Fig. 3, what is the value of collector current?
Vcc = 20V
RC = 4.7k Ω
RB
680 kΩ
β = 120
VCE(sat) = 0.2 V
VBE = 0.7 V
Fig. 3
A. 1.85 mA
Fig. 4
B. 15.5 µA
C. 4.2 mA
D. 1.93 mA
9. The unity feedback system with forward transfer function G(s) has no openloop poles in the
right half s-plane. If the Nyquist plot of G(s) is as shown in the Fig. 4, then:
A. The system is stable
B. The system is unstable with one pole in the right-half of the s-plane
C. The system is unstable with two poles in the right-half of the s-plane
D. Stability cannot be determined
10. Phase-angle error in a CT can be reduced by
A. reducing number of secondary turns.
B. using thin conductors for the primary winding.
C. using good quality, low loss steel for core.
D. all of the above.
11. A slide-wire potentiometer has 10 wires of 1 m each. With the help of a standard voltage
source of 1.018 volt, it is standardised by keeping the jockey at 101.8 cm. If the resistance
of the potentiometer wire is 1000 , then the value of the working current is
A. 1 mA
21 May, 2017
B. 0.5 mA
C. 10 mA
D. 0.1 A
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Register Number:
12. A synchronous motor is operating at no load and at unity power factor. If the field current
and the current will
.
is increased, the pf will be
A. lagging, increase
decrease
B. lagging, decrease
C. leading, increase
D. leading,
13. In electrodynamometer-type wattmeters, current coil is made of two sections
A. to reduce power loss.
B. to produce uniform magnetic field.
C. to prevent Eddy-current loss.
D. to reduce errors due to stray magnetic field.
14. In a closed-loop speed-controlled separately excited dc motor drive, the mechanical load at
the shaft is suddenly changed to a higher value. Read the following statements and choose
the correct combination applicable to the transient situation.
1. Speed decreases, and settles back to the previous value.
2. Speed decreases, and settles to a lower value.
3. Armature current decreases, and settles back to the previous value.
4. Armature current increases, and settles to a higher value.
5. Armature current increases, and settles back to the previous value.
A. 1 & 3
B. 1 & 5
C. 1 & 4
D. 2 & 4
15. A single-phase voltage-source inverter is feeding an RL load. The inverter is modulated with
sinusoidal pulse-width-modulation scheme. The switching frequency of the inverter is more
than 25 times the frequency of the sine wave used to generate the gating pulses. Read the
following statements and choose the correct combination applicable to the circuit.
1. The load voltage is of PWM shape.
2. The load voltage is predominantly of sinusoidal shape with a little harmonic ripple.
3. The load current is of PWM shape.
4. The load current is predominantly of sinusoidal shape with a little harmonic ripple.
A. 1 & 3
B. 2 & 3
C. 1 & 4
D. 2 & 4
16. A star connected synchronous generator has synchronous impedance of 0 + j5.0Ω per phase.
It delivers a zpf leading current of 20A at 400 V. Its generated emf per phase is
A. 131 V
B. 331 V
C. 300 V
D. 500 V
17. Two buses A & B in a power transmission network are connected with a transmission line
of j 0.1 p.u. impedance. The voltages at the buses are VA =1.02 6 50 and VB =1.05 6 00 . The
active power (P) and reactive power (Q) flows in the network will be
21 May, 2017
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Register Number:
A. P flows from A to B and Q flows from B to A
B. P flows from B to A and Q flows from A to B
C. both P & Q flows from B to A
D. both P & Q flows from A to B
18. A 10 MHz clock is applied to a cascaded counter consisting of a mod 5, mod 8 and mod 10
counters. The lowest output frequency possible is
A. 2.5 kHz
B. 25 kHz
C. 5 MHz
D. 2 MHz
synchronous
19. A synchronous condenser is an
at its shaft.
with
load
A. under excited / motor / full B. over excited / generator / no
C. over excited / motor / no D. under excited / generator / full
20. The Figure 5 shows a simple dc-dc converter used for heating control. If the switch ‘S’ is
operated with a duty ratio of 0.25, what is the power dissipated in the 10Ω resistor?
S
f (t)
1
10Ω
Vdc = 100V
B. 1000W
-1
− T2
Fig. 5
A. 62.5W
t
0
C. 250W
T
2
Fig. 6
D. Data not sufficient.
21. The Fourier series expansion f (t) = a0 +
∞
P
(an cos nωt + bn sin nωt) of the periodic signal
n=1
shown in Fig. 6 will contain the following nonzero terms.
A. a0 and bn , n = 1, 3, 5, . . . ∞
B. an , n = 1, 2, 3, . . . ∞
C. an , n = 1, 3, 5, . . . ∞
D. a0 , an and bn , n = 1, 3, 5, . . . ∞
22. A shunt reactor rated 100 MVAr at 400 kV, 50 Hz is connected to a power transmission
network for voltage regulation. It is operated at 105% of its rated voltage and 99% of its
rated frequency. The reactive power absorbed by the reactor will be
A. 101.01 MVAr
B. 110.25 MVAr
C. 111.36 MVAr
D. 106.06 MVAr
23. Two identical alternators, each rated for 100 MVA, 11 kV, having sub-transient reactance of
10% are working in parallel. The short circuit level at the bus bar is
A. 200 MVA
21 May, 2017
B. 500 MVA
C. 1000 MVA
D. 2000 MVA
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Register Number:
24. Identify the correctness of the 8-bit data alongwith parity 101010101 received by an even
parity system.
A. True data
B. Wrong data
C. Cannot predict
D. Some bits are missing
25. A 2 pole, 50 MVA, 50 Hz, turbo-generator has a moment of inertia of 9 × 103 kg-m2 . The
inertia constant H in MJ/MVA is
A. 17.746
B. 8.873
C. 4.436
D. 13.309
26. The Ybus matrix of a 4 bus system in p.u. is given by Ybus


−8 2
3
1
 2 −5 1
0
. The
= j
3
1 −9 4 
1
0
4 −6
buses having shunt elements are
A. 2 and 4
B. 2, 3, and 4
C. 1,3, and 4
D. 1,2,3, and 4
27. In Figure 7, the symbol shown is that of
D
A
B
i/p
G
S
o/p
f2
f1
Fig. 8
Fig. 7
A. Depletion type p-channel MOSFET B. Depletion type n-channel MOSFET
C. Enhancement type p-channel MOSFET D. Enhancement type n-channel MOSFET
28. Figure 8 shows a cascade arrangement of two filters. “A” is a low-pass filter with cut-off
frequency f1 and “B” is a high-pass filter with cut-off frequency f2 . Read the following
statements and choose the correct combination applicable. Neglect any loading effect.
1. For f1 > f2 , the combination will act as a band-pass filter
2. For f1 > f2 , the combination will act as a band-reject filter
3. For f1 < f2 , the combination will act as a band-pass filter
4. For f1 < f2 , the combination will act as a band-reject filter
5. For all input, the combination will act as an all-pass filter
A. 2 and 3 are TRUE.
C. 1 and 4 are FALSE.
B. 1 and 4 are TRUE.
D. Only 5 is TRUE
29. Which of the following energy generation methods can be classified as “renewable”?
I. Nuclear
II. Hydro
III. Solar
IV. Biomass
V. Natural Gas
A. II, III, IV and V
21 May, 2017
B. III and IV
C. I, II, III and IV
D. II, III and IV
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GEC Idukki|EE|AP(Contract) Screening Test
Register Number:
30. When a 2 kHz sinusoidal signal is viewed in an oscilloscope, half a cycle is displayed. What
would be the sweep frequency?
A. 1 kHz
B. 2 kHz
C. 4 kHz
D. 0.5 kHz
31. To conduct load test on a dc shunt motor, it is coupled to a generator which is identical
to the motor. The field of the generator is also connected to the same supply source as
the motor. The armature of the generator is connected to a load resistance. The armature
resistance is 0.02 pu. Armature reaction and mechanical losses can be neglected. With rated
voltage across the motor, the load resistance across the generator is adjusted to obtain rated
armature current in both motor and generator. The pu value of this load resistance is
A. 1.0 pu
B. 0.98 pu
C. 0.94 pu
D. 0.96pu
32. The low-frequency gain of the low-pass filter shown in Fig. 9 is
100 kΩ
X
0.01 µF
vi
1 kΩ
Y
vo
Fig. 10
Fig. 9
A. 10 dB
B. 20 dB
C. 30 dB
D. 40 dB
33. In figure 10, X is a square wave with frequency 50 kHz. All the gates in the circuit have a
propagation delay of 10 ns. The output Y will
A. be having 10 ns wide high-to-low notches.
pulses. C. always be 1. D. always be 0.
B. be having 10 ns wide low-to-high
34. An op-amp is used in comparator mode. A sinusoidal signal v(t) = 1 − sin ωt is applied to
the non-inverting terminal and a dc voltage of 1 V is applied at the inverting terminal. The
output signal will be
A. a square wave in phase with sin ωt
B. a square wave 180o out of phase with
sin ωt.
C. positive always. D. negative always.
35. Neglecting the effects of stator resistance and leakage reactance, if the applied voltage is
halved, then the developed torque in a three-phase squirrel-cage induction motor will
A. remain same
B. increase by a factor of 2
C. reduced to half that at full voltage
D. reduced to
1
th of that at full voltage
4
36. For a two-port symmetrical bilateral network, if the transmission parameters A=3, B=1Ω,
value of parameter C is
A. 3
B. 8 S
21 May, 2017
C. 8 Ω
D. 9
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GEC Idukki|EE|AP(Contract) Screening Test
Register Number:


2 2 2
37. The rank of the matrix 2 2 2 is
2 2 2
A. 0
B. 1
C. 2
D. 3
√
38. In the circuit of figure 11, vs (t) = 10 2 cos (1000t) V. The values of the resistance RL and
the capacitance C such that maximum average power is absorbed by the load are:
6Ω
Load
4 mH
10 Ω
RL
vs (t)
C
3Ω
10 V
10 µF
√
vs (t) = 10 2 cos (1000t) V
Fig. 11
A. 2 Ω, & 0.25 mF
B. 2 Ω, & 4 mF
1H
t=0
Fig. 12
C. 6 Ω, & 0.25 mF
D. 6 Ω, & 4 mF
39. Initially, the circuit shown in Fig. 12 was relaxed. If the switch is closed at t=0, the value
d2 i
di
of i(0+), (0+) and 2 (0+) will respectively be
dt
dt
A. 0, 10 and -100 B. 0, 10 and 100 C. 10, 100 and 0 D. 100, 0 and 10
→
−
40. Given a vector field F , the divergence theorem states that
R→
R→
− →
−
− →
−
A. F · d S = ∇ × F dV
S
V
R→
R→
−
→
−
− →
−
B. F × d S = ∇ · F dV
V
S
R→
R→
−
→
−
− →
−
C. F × d S = ∇ × F dV
S
V
R→
R→
− →
−
− →
−
D. F · d S = ∇ · F dV
S
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V
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