OCET-2012
Question Booklet Series : A
Sr. No. :
Important : Please consult your Admit Card / Roll No. Slip before filling your Roll Number on
the Test Booklet and Answer Sheet.
Roll No.
Answer Sheet Serial No.
Signature of the Candidate :
Paper : I
Subject : M.E. (Instrumentation and Control)
Time : 90 minutes Number of Questions : 75 Maximum Marks : 75
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question,
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in the
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in the
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deducted for each
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permitted inside the examination hall. Use of calculators is not allowed.
M.E. (Instrumentation and Control)-A/FRH-41343 2
M.E. (Instrumentation and Control)-A/FRH-41343 3 [Turn over
M.E. (Instrumentation and Control)/A
1. The open loop DC gain of unity negative feedback system with closed-loop transfer
function 7 13
4


ss
s
2 is :
(A) 4/13 (B) 4/9
(C) 4 (D) 13
2. For a second order system, if both the roots of the characteristic equation are real and
equal then the value of damping ratio will be :
(A) < 1 (B) Zero
(C) 1 (D) 1
3. An electromechanical closed-loop control system has the following characteristics
equation
S3 + 6KS2 + (K + 2) S + 8 = 0 where K is the forward gain of the system. The
condition for closed-loop stability is :
(A) K = 0.528 (B) K = 2
(C) K = 0 (D) K = –2.528
4. If the open-loop transfer function is a ratio of a numerator polynomial of a degree 'm'
and
a denominator polynomial of a degree 'n', then the integer (n – m) represents the
number of :
(A) break away points (B) unstable poles
(C) separate root loci (D) asymptotes
5. The open loop transfer function of a unity feedback control system is s 33
10
. The gain
margin of the system will be :
(A) 20 dB (B) 40 dB
(C) 60 dB (D) 80 dB
6. A system has ten poles and two zeros. The slope of its highest frequency asymptote in its
magnitude plot is :
(A) –40 dB/decade (B) –160 dB/decade
(C) –200 dB/decade (D) –240 dB/decade
7. u
1
0
x
01
12
X

; Y = [b 0] x, where be is unknown constant the system is :
(A) observable for all values of b (B) unobservable for all values of b
(C) observable for all non–zero values of b (D) unobservable for all non-zero values of b
M.E. (Instrumentation and Control)-A/FRH-41343 4
8. A function f(t) = sin 1.1 t + sin 3.3 t has the time period :
(A) /1.1 (B) 2/1.1
(C) 2/3.3 (D) 3/2.2
9. The Nyquist plot of a loop transfer function G(jw) H(jw) of a system encloses the (–1, 0)
point. The gain margin of the system is :
(A) Less than zero (B) Zero
(C) Greater than zero (D) Infinity
10. Which one of the following is a non-valid BCD CODE ?
(A) 0111 1001 (B) 0101 1011
(C) 0100 1000 (D) 0100 1001
11. Skip distance is independent of :
(A) frequency (B) state of ionization
(C) transmitting power (D) types of wave propagation
12. With usual notations a 2-port network satisfies the condition
ADBC
3
4
2
3 
The Z11 of the network is :
(A) 5/3 (B) 4/3
(C) –2/3 (D) 1/3
13. The unit of poynting vector is :
(A) power (B) energy density
(C) energy (D) power density
14. Tangential component of the electric field on a perfect conductor will be :
(A) Same as normal field component and 180o out of phase
(B) Zero
(C) Same as normal field component and 90o out of phase
(D) Infinite
15. For an AM wave having a power of 800 W at its carrier frequency and modulation
index
of 90%, the power content of each side band is :
(A) 81 W (B) 162 W
(C) 200 W (D) 400 W
M.E. (Instrumentation and Control)-A/FRH-41343 5 [Turn over
16. A PWM signal can be generated by :
(A) an astable multivibrator (B) an monostable multivibrator
(C) integrating a PPM signal (D) differentiating a PPM signal
17. The transfer function
10 100
10
()
()
2
1
2


ss
s
Vs
V s is for an active :
(A) low pass filter (B) band pass filter
(C) high pass filter (D) all pass filter
18. The sensitivity of a photo diode depends upon :
(A) light intensity and depletion region width
(B) depletion region width and excess carrier life time
(C) excess carrier life time and forward bias current
(D) forward bias current and light intensity
19. If a mod-6 counter is constructed using 3 flip-flops, the counter will skip :
(A) 4 counts (B) 3 counts
(C) 2 counts (D) Zero counts
20. The open-loop gain of an operational amplifier is 105, a signal of 1 mV is applied to the
inverting input with non-inverting input connected to the ground. The supply voltages are
± 10 V. The output of the amplifier will be :
(A) +100 V (B) –100 V
(C) +10 V (D) –10 V
21. Given (125)8 = (203)R, the value of the radix R will be :
(A) 16 (B) 10
(C) 8 (D) 6
22. Consider the following set of instructions :
STC
CMC
MOV A, B
RAL
MOV B, A
This set of instructions :
(A) doubles the number in Register by B (B) multiplies B by A
(C) divides the number in Register by 2 (D) adds A and B
M.E. (Instrumentation and Control)-A/FRH-41343 6
23. In a digital voltmeter, the oscillator frequency is 400 kHZ, the ramp voltage falls from
8 V to 0 V in 20 msec. The number of pulses counted by the counter is :
(A) 8000 (B) 4000
(C) 3200 (D) 1600
24. Which of the following transducers can be used for magnetic flux density measurement
?
(A) LVDT (B) Synchro
(C) Hall effect transducer (D) Thermocouple
25. The position telemetering system using synchros is :
(A) a pulse telemetering system (B) an RF telemetering system
(C) a DC telemetering system (D) an AC telemetering system
26. The input impedance of a CRO is nearly :
(A) Zero (B) 10 ohm
(C) 100 ohm (D) 1 M ohm
27. Which of the following is basically a current sensitive instrument ?
(A) PMMC instrument (B) CRO
(C) Electrostatic instrument (D) FET input electronic voltmeter
28. The most commonly used null detector in power frequency ac bridge is a :
(A) vibration galvanometer (B) d'Arsonval galvanometer
(C) ballistic galvanometer (D) tachometer
29. Which of the following instrument has the lowest resistance ?
(A) ammeter (B) voltmeter
(C) frequency meter (D) megger
30. The shunt resistance in an ammeter is usually :
(A) Zero (B) One
(C) X (D) X
XY
M.E. (Instrumentation and Control)-A/FRH-41343 7 [Turn over
31. Which of the following does not require auxiliary circuitry if used as transducer ?
(A) capacitance (B) photocell
(C) resistance (D) inductance
32. The zero error of an instrument is :
(A) gross error (B) systematic error
(C) random error (D) indefinite error
33. The reliability of a measuring instrument means :
(A) the life of instrument
(B) degree to which repeatability continues to remain within the specified limits
(C) the extent over which the characteristics remain linear
(D) all of these
34. A digital voltmeter has a read out range from 0 to 9999. When full scale reading is
9.999 V the resolution of the full scale reading is :
(A) 0.001 (B) 1000
(C) 3 digit (D) 1 mV
35. Which of the following connections of the three phase transformer causes interference
to the nearby communication system ?
(A) Delta-star (B) Star-delta
(C) Star-star (D) Delta-delta
36. Scott-connections are used for :
(A) Single phase to three phase transformation
(B) Three phase to single phase transformation
(C) Three phase to two phase transformation
(D) Single phase to any no phase transformation
37. Distribution transformers have core losses :
(A) > copper loss (B) < copper loss
(C) = copper loss (D) = (copper losses)/2
38. For a slip ring induction motor, if the resistance is increased, then :
(A) Starting torque and efficiency increases
(B) Starting torque and efficiency decreases
(C) Starting torque decreases but efficiency increases
(D) Starting torque increases but efficiency decreases
M.E. (Instrumentation and Control)-A/FRH-41343 8
39. An amplifier with no feedback has a gain bandwidth product of 5 MHz. Its closed loop
gain is 50. The new bandwidth will be :
(A) 250 kHz (B) 100 kHz
(C) 10 kHz (D) 20 kHz
40. Skin effect exists in :
(A) cable carrying dc current (B) dc transmission line only
(C) ac transmission line only (D) dc as well as ac transmission lines
41. Single core cable are usually not provided with :
(A) rubber insulation (B) paper insulation
(C) steel armoring (D) lead sheath
42. In an RC phase shift oscillator, the minimum number of R-C networks to be connected
in
cascade will be :
(A) 1 (B) 3
(C) 2 (D) 4
43. Bundled conductors are mainly used :
(A) to increase the shunt capacitance (B) to decrease the shunt capacitance
(C) to increase the series reactance (D) to decrease the series reactance
44. Capacitor with initial charge Qo at t = 0+ acts as :
(A) open circuit (B) short circuit
(C) voltage source (D) current source
45. A voltage wave containing 20% harmonics is applied to an inductor. The percentage of
third harmonics in the current wave will be :
(A) much less than 20% (B) much more than 20%
(C) 20% (D) 10%
46. The voltages measured across R, L and C in a series RLC circuit connected with a
sinusoidal source are 3 V, 14 V and 10 V respectively. The input voltage is :
(A) 27 V (B) 5 V
(C) 24 V (D) 10 V
47. Bandwidth of an RF tuned amplifier is dependent on :
(A) Q-factor of the tuned input circuit
(B) Quiescent operating point
(C) Q-factor of the tuned output circuit
(D) Quiescent operating point and Q factor of input circuit
M.E. (Instrumentation and Control)-A/FRH-41343 9 [Turn over
48. Leading power factor implies that :
(A) current leads the voltage (B) current lags behind the voltage
(C) voltage leads the current (D) current and voltage aline
49. Latching current of an SCR is ________ of the rated current.
(A) Below 10% (B) 10–20%
(C) 20–25% (D) 25–30%
50. Breakdown in a silicon UJT was observed to occur at a voltage of 6 V for a VBB = 10 V.
Its (stand off ratio) is :
(A) 1.66 (B) 0.6
(C) 0.54 (D) 0.4
51. In FM, if depth of modulation is doubled, power transmitted :
(A) becomes double (B) remain unaltered
(C) becomes 1.5 times (D) becomes  2 times
52. Base modulation is used in TV transmission because :
(A) power required is small (B) large power output and better efficiency
(C) high degree of linearity (D) less degree of linearity
53. Relaxation oscillator is one which :
(A) produces sinusoidal output (B) produce non sinusoidal output
(C) relaxes indefinitely (D) oscillates continuously
54. A differential amplifier essentially consist of :
(A) two input and two output terminals
(B) only resistors and transistors
(C) two transistors
(D) two CE amplifiers having their emitters directly coupled to each other
55. In Fourier expression, the Coefficient a0 is found by :
(A)
∫

/2
/2
()
1T
T
f t dt
T
(B) ∫

/2
/2
()
2
1T
T
f t dt
T
(C) ∫

/2
/2
( ) cosω
1T
T
f t t dt
T (D) ∫
T
f t dt
T
0
()
2
M.E. (Instrumentation and Control)-A/FRH-41343 10
56. The figure below shows the circuit of which one of the following ?
(A) Bi-stable multi-vibrator (B) Schmitt trigger
(C) Mono-stable multi-vibrator (D) Astable multi-vibrator
57. In the circuit given below, both transistors have same voltage VT. What is the
approximate value of the highest possible output voltage Vout, if Vin can range from 0 to
VDD ? Assume 0 < VT < VDD .
(A) VDD – VT (B) VDD
(C) VT (D) Zero
58. The maximum power in the shown load is :
(A) 25 W (B) 30.6 W
(C) 62.5 W (D) 110 W
Vin
vO1 C
+ VDD
R
vO2
Vout
Vin
VDD
~ 50 0o V
10 j 20 
ZL
M.E. (Instrumentation and Control)-A/FRH-41343 11 [Turn over
59. Which one of the following sets of equations is independent in Maxwell's equations ?
(A) Two curl equations
(B) Two divergence equations
(C) Both curl and divergence equations
(D) Two curl equations combined with continuity equation
60. The signal flow graph for a system is shown below. The number of forward paths is :
(A) 1 (B) 2
(C) 3 (D) 4
61. The equivalent inductance of system shown below is :
(A) L1 + L2 (B) L1 + L2 + 2M
(C) L1 + L2 – 2M (D) L1 – L2 – 2M
62. The current flowing through the load resistor RL in the circuit is :
(A) 0.2 A (B) 0.25 A
(C) 0.5 A (D) 1.0 A
x1
a12
x2
a23 a34 a45
a44
a42
x5
x x 43
a32 a35
a52
M
L1 L2 1
1'
+
–
6V
1 1 
1 1 

6
5
RL
M.E. (Instrumentation and Control)-A/FRH-41343 12
63. The Fourier series is expressed by :
(A) Σ



1
( ) 0 ( cosω sin ω )
n
f t a an t bn t
(B) Σ



1
( ) 0 ( cos ω sin ω )
n
f t a an n t bn n t
(C) Σ



1
( ) ( cos ω sin ω )
n
f t an n t bn n t
(D) Σ



1
( ) 0 (cos ω sin ω )
n
ftantnt
64. Which of the following is not the tree of the given graph ?
(A) (B)
(C) (D)
435
12
5
M.E. (Instrumentation and Control)-A/FRH-41343 13 [Turn over
65. The value of i9 in the circuit is :
(A) 2A (B) –2A
(C) –5A (D) 5A
66. The waveform shown below is given to dc meter. The reading of the meter will be :
(A) 5 mA (B) 10 mA
(C) 7.1 mA (D) 6.3 mA
67. The circuit shown in the figure is :
(A) a voltage source with voltage
R1||R2
rV
(B) a voltage source with voltage V
R
rR
1
|| 2
(C) a current source with current r
V
RR
rR
·
||
12
2
(D) a current source with current r
V
RR
R
·
12
2

i8 = 6 A i9
i6 ii 5 4
i7 = 3 A
i3= 4 A
i2
i1 = 2 A
10 mA
I
t
+
V
R1
R2
+
–
Load
r
68. If RST is written in a program the problem will jump to location :
(A) 0020 H (B) 0024 H
(C) 0028 H (D) 002C H
69. In the switching circuit shown in the figure below, RC time constant is much switching
longer as compared to the time period of its input pulse signal.
Vout of the circuit is in the form :
(A) (B)
(C) (D)
70. Differential mode voltage gain of the amplifier for the figure is :
(A)
ic
fe L
h
hR
(B)
E
L
2R
R
(C)
E
L
R
R
(D)
E
fc L
R
hR
t
O
t
+V
–V
+V
O
t
+V
O
RR
vo
o1 o2
R
vu
v2
v1
Vin
Ot
Vin
Vin
C
R Vout
O
t
–V
M.E. (Instrumentation and Control)-A/FRH-41343 14
71. AC-to-DC circulating current dual converters are operated with which of the following
relationship between their triggering angles ?
(A) 1 – 2 = 180 (B) 1 + 2 = 360
(C) 1 + 2 = 180 (D) 1 + 2 = 90
72. The fully controlled SCR converter in the figure is fed from a single-phase source.
When
the firing angle is zero, the DC output voltage of the converter is 300 V. What will be the
output voltage for a firing angle of 60o, assuming continuous conduction ?
(A) 150 V (B) 210
(C) 300 (D) 100
73. The differential equation 25x 0
dt
dx
10
dt
dx
2
2
will have a solution of the form :
(A) (C1 + C2 t) e–5t (B) C1e–2t
(C) C1e–5t + C2 e5t (D) C1e–5t + C2e2t
74. The Laplace transform of
t
e at  e bt is :
(A) s b
sb


(B)
sb
sa
Log


(C)
a
b

(D)
sa
sb


75. A plane electromagnetic wave travelling along = z direction, has its electric field given
by
Ex = 2 cos (t) and Ey = 2 cos(t + 90). The wave is :
(A) Linearly polarized (B) Right circularly polarized
(C) Left circularly polarized (D) Elliptically polarized
+
Vdc