BKU-14144-A 1 [Turn over
ROUGH WORK

1. Current I in the circuit shown below is 2 .
I



2 . 100 V

4 .

Fig. 1
5 A 10 A
25 A 50 A


2. Ohm’s Law for A.C. is
V V
(A) I I
R X R2 X2

V V(C) I I
2 2
ZR –X
3. To generate one unit of electricity in a thermal plant will consume the amount of coal— approximately
Less than 1 kg 1000 kg
1 ton 10 kg


4. In purely resistive circuits
Power consumed is zero Power factor is zero
Power factor is one Only reactive power flows


5.
In given RC circuit voltage across R is 100 V and voltage across C is 100 supply voltage should be

6.
In a battery when maximum power is delivered. Efficiency of the battery is
100% 50%
75% 25%



7. Power in a three-phase circuit is given by
3 VLIL cos f where f is
angle between line voltage, line current
angle between line voltage, phase current
angle between phase voltage, phase current
angle between phase voltage, line current



8.
Which of the following is 4-wire system
Delta Star
Both Delta and Star Neither Delta, nor Star



9.
In a three-phase supply, floating neutral is undesirable because it may result in
unequal line voltages high voltage
low voltage none of the above



10.
Time constant of an RC circuit is given by



Fig. 5 100 V 200 V 100100 22

R RC
C
C R
s 3
11. If then is
2e–t 1e–2t 1e–2t – 2e–t
2e–t – 1e–2t 1e–2t 2e–t


12. Final Value theorem is given by
Lim Lim Lim Lim (B)
t.0s.0t.8 s.8
Lim Lim Lim Lim (D)
t.8 s.0t.0s.8
BKU-14144-A 4

V2(s)
13. For the circuit shown in fig. is given by
C

Fig. 13 1RC RCs 1RCs RCs 1RCs 1 1RCs s
14. T.F. of the system is given by


(A) G1 G1 1 1 1 G1 G 1 1 – G1 G Fig. 14
15. 1)2ss(s 1 V V 2 1 2 type 0 system order 0 system is type 1 system order 1 system

16. Root locus gives the location of the roots on s plane as varies.
time frequency
gain amplitude


17. In Bode plot magnitude is measured as
Log10 bels 10 Log10 decibels
20 Log10 decibels Log10 decibels


18. If R 1 ohm, C 1 Farad and 100 V D.C. is switched across the circuit. Voltage across the
capacitor will reach 63.2 volts in seconds.
R
1 second
3 seconds


K
19. For sT 1
system is stable, gain margin 0
system stable, gain margin 8


20. Phase margin is measured when
Phase cuts –180º
Gain crosses 0 db


21. Characteristic equation is given by s3 2s2 4s K system will be stable if K is
0 K 8
K 8


BKU-14144-A

C



Fig. 18
2 seconds
5 seconds
system unstable, gain margin 0
None of the above
Phase cuts 180º
Gain crosses 20 db
0 K 16
K 0


6
22. A power capacitor has a capacitance of 26.5 µF and voltage rating of 100 kV. It is charged to a d.c. potential of 100 kV. How much energy is stored in the device
132,500 J 132 J
1 kJ 26.5 Watts


23. Thermal time constant of a transmission line is of
few seconds few minutes
few hours few days


24. A secondary cell having 20 hr charge rate of 10 A and delivering 5 A for 36 hr on discharge with a mean terminal voltage of 1.96 V. The terminal voltage on charge has a mean value of 2.35. Watt-hour efficiency is
25% 50%
75% 90%


25. Find trickle current to be sent through an idle accumulator battery having a capacity of 50 Ah rating in order to keep it full charged, when the discharge rate due to local action is of the normal discharge rate.
5 mA 50 mA
500 mA 450 mA


26. Two underground cables having conductor resistances 0.7 ohm and 0.5 ohm and insulation resistances of 300 M. and 600 M. respectively are joined in series. Resultant conductor and insulation resistances are
1.2 900 M. 0.3 200 M.
1.2 200 M. 1.2 900 .


27. A resistance R is connected in series with a parallel circuit comprising two resistances of 12 . and 8 . respectively. The total power dissipated in the circuit is 70 when applied voltage is 20. R is
91 . 9.1 .
.91 . 910 .


28. For the circuit shown, difference of potential between X and Y is 4 V
–
2 .

X

– 3 . 5 .3 .2 V 4 V
–
Y
Y is 3.7 V below X Y and X are at the same potential
Y is 3.7 V above X X is 4 V below Y


29. A battery consists of 10 cells each with an e.m.f. of 2 V and internal resistance of 0.2 . are connected in parallel. Power lost in a resistance of .25 . across the circuit is
493 W 15.7 W
49.3 W 157 W


30. Calculate Impedance, Current power, Power factor.
200 V

50 mH


50 Hz
100 µF

Fig. 30
16.1 12.4 0 lead 16.1 12.4 1 lead
8.55 24.8 0 lead 8.55 24.8 1 lead


31.
A 12 kV, 50 Hz, 1 phase alternator is connected to an unloaded cable having a capacitance of 2.03 µF. If the total circuit inductance is 0.2 what harmonic in the supply voltage

32.
100 V D.C. is applied across a coil having R 2 . and L 10 H. Value of the current after

7.5 sec is
50 A 38.8 A
19.4 A 58.2 A



33.
When switch is closed at that instant current increases at the rate of 4 A/sec. applied voltage is


would produce resonance in the circuit First Fifth Third Seventh
BKU-14144-A 8




Fig. 33
20 V 40 V
60 V 80 V


34. A resistor is connected across the terminals of a 20 µF capacitor which has been previously charged to a p.d. of 500 V. If the p.d. falls to 300 V in 0.5 minutes then R is
294 . 2940 .
2.94 k. 2.94 M.


35. In an RLC circuit voltage across L and C is each 10 V. Supply voltage is

Fig. 35 10 V 30 V 20 V 15 V

36. An ideal moving iron voltmeter M will read


Fig. 36
7.07 V 14.14 V
12.25 V 15 V


37. A single phase full-bridge diode rectifier delivers a constant load current of 10 A. Average and R.M.S. values of source current are respectively
5 10 A 10 10 A
5 5 A 10 A


38. Capacitor filter is ideal for currents which are
small medium
large very large


di

39. rating of an SCR is specified for its :
dt
decaying anode current decaying gate current
rising gate current rising anode current


40. In a single phase semi converter, for continuous conduction, each SCR conducts for
a p
a p p – a


41. Each diode of a 3 phase half-wave diode rectifier conducts for
60º 120º
180º 90º


42. Three-phase ac to dc converter which requires neutral point connection is
Three phase semi converter Three phase full converter
Three phase half wave converter Three phase full converter with diodes


43. For the triangular waveform shown in fig., RMS value of voltage is
1


T 3T 2T
T
22


Fig. 43
1
1

(B)
6 3
1 2 (D)
3 3
44. In d.c. choppers, per unit ripple is maximum when duty cycle is
0.2 0.5
0.7 0.9


45. A single phase inverter has square wave output voltage. What is the fifth harmonic component in relation to the fundamental component
40% 30%
20% 10%


46. Bulk power transmission over long HVDC lines are preferred on account of
Low cost of HVDC terminals No harmonic problems
Minimum line power losses Simple protection


47. The error which is repetitive in nature is
observational error environmental error
random error systematic error


48. The smallest change in the value of input variable being measured, that will cause a change in the output signal of the instrument is termed as
hysteresis drift
resolution threshold


BKU-14144-A 11 [Turn over
49. Repeatability of the instrument with respect to a given fixed input is
accuracy precision
resolution sensitivity


50. Radius of a sphere was estimated as (50 ± 0.5 mm). Estimated error in its mass is
3%
0·1% 10%


51. A solar cell is
Photovoltaic transducer Photoemissive transducer
Photoconductive transducer Photoresistive transducer


52. LVDT stands for
Low voltage digital transducer
Linear voltage differential transducer
Least varying differential transformer
Linear variable differential transformer


53. CRO is instrument.
Low input impedance High input impedance
Zero input impedance None of the above


54. Audio frequency range lies
Between 20,000 to 30,000 Hz Between 20 and 20,000 Hz
Above 40,000 Hz Around 1000 Hz


55. Function of steel wire in ACSR conductor is to
compensate for skin effect
take care of surges
provide additional mechanical strength
reduce inductance


56. Resistance of earth should be
Infinite High
Low Minimum possible


57. Main limitation of the PMMC instrument is
High power consumption
Absence of effective eddy current damping
Low torque/weight ratio
High cost relative to moving-iron instrument


58. Electrodynamic type instruments can be used to measure
a.c. input only d.c. input only
Both a.c., d.c. None of these


59. A rectifier type moving coil instrument respond to
r.m.s. values of all waveforms
Average values of all waveforms
R.M.S. values of only sinusoidal waveforms
Peak values of all waveforms


60. Controlling torque of an electrical measuring instrument is proportional to (B)Q2
1 (D)
Q
61. For measuring currents in the radio frequency range, which of the following instruments is used
Moving iron type Moving coil type
Thermocouple type Rectifier type


62. Operating frequency range of a rectifier type instrument is
Upto 20 Hz Between 20 Hz – 20 kHz
From 20 kHz to 50 kHz D.C. only


63. Tachometer is a special case of
a.c. motor d.c. generator
induction motor universal motor


BKU-14144-A 13 [Turn over

64. Linear actuator converts
Mechanical Energy to Electrical Energy
Electrical Energy to Mechanical Energy
Electrical Energy to Linear Motion
Potential Energy to Kinetic Energy


.

t
.

65.

L

. ..

.

f(t) dt
. ..

is
0
sn


66. PID controller is represented as
1 t e edt
T .
i
0 1 t de e edt T
Ti . ddt
0
67. In a closed loop control system
Output is dependent on input
Output is independent of input


68. Megger is used for
open circuit test
continuity test
s n
s e Td de
dt
None of these
Input is dependent on output
None of these
short circuit test
all of the above


69. Current transformers are used to extend the range of
ammeters current coil of wattmeters
current coil energy meters all of the above


70. Potentiometers are used to measure
Voltage Current
Resistance All of the above


71. A milliammeter of 3 ohms resistance reads a maximum current of 150 milliamperes. How it can be used as a voltmeter to read upto 15 volts
Connect a resistance of 9.7 ohms in series with the meter
Connect a resistance of 9.7 ohms in parallel
Connect of resistance of 97 ohms in series
Connect of resistance of 97 ohms in parallel


72. Base units in SI system are
Meter, kilogram, second, ampere, kelvin
Meter, kilogram, second
Meter, kilogram, second, ampere, kelvin, candela
Meter, kilogram, second, ampere


73. Wattmeters are type while energy meters are type instruments.
Indicating, Recording Indicating, Integrating
Integrating, Indicating Integrating, Recording


74. Laplace transform of a decaying exponential function is
A A (B)
s a s– a
s s (D)
s a s– a
75. Laplace transform of unit impulse function is
1 1
s s None of these
76. Acceptor type semiconductor is formed by adding impurity of valency
(A) 3
(C) 5
77. Fermi level represents the energy level with probability of its occupation of
0 50%
75% 100%


78. Primary function of a clamper circuit is to
Suppress variations in signal voltage
Raise positive half cycle of the signal
Lower negative half cycle of the signal
Introduce d.c. level into an a.c. signal


79. Photodiodes belong to category.
Photoconductive Photovoltaic
Photoemissives None of the above


80. Thermistor has
Zero temperature coefficient of resistivity
Positive temperature coefficient of resistivity
Negative temperature coefficient of resistivity
None of the above


81. Input resistance of a transistor is much than its output resistance.
Less Higher
Same None of the above


82. Reading in d.c. milliammeter is


Fig. 82
5.175 mA 15.175 mA
.5175 mA 7.5 mA


83. R.M.S. current in half wave rectifier is and full wave rectifier is I I
2, Im/2
mm/
2 Im/
3 Im/3 Im/
3
84. In Y Parameters Y11 is
Short circuit input admittance
Short circuit forward transfer admittance
Short circuit output admittance
None of the above


85. h-parameters h11 and h21 for the circuit shown in fig. 15 .

Fig. 85
15 1 15 –1
.2 moh, 1 .2 moh, –1


86. Transistor amplifier has lowest input impedance in
CB configuration CE configuration
CC configuration None of these


87. Improper biasing of a transistor circuit leads to
distortion of output signal faulty location of load line
excessive heating at collector point heavy loading of emitter terminal


88. In an amplifier coupling capacitors are used to
Match the impedances
Control the output
Limit the bandwidth with input or output
To prevent d.c. mixing


89. Multistage amplifiers are used in order to achieve greater
Voltage amplification Frequency response
Power gain All of the above



90. The main component responsible for the fall of gain of an RC-coupled amplifier in low frequency range is
Coupling capacitor Resistor Re
Biasing system The device (Transistor)


91. An amplifier with Zi 2 k. has a voltage gain A 2000. If a negative feedback of B 0.01 is applied to it, what shall be input impedance of feedback amplifier
42 . 420 .
4200 . 42000 .


92. Negative feedback in amplifier
reduces voltage gain increase voltage gain
does not affect voltage gain can convert it into oscillator


93. A power transistor working in class A operation has zero signal power dissipation of 10 Watt. If the a.c. output power is 3 Watt, collector efficiency and power rating of transistor are 10 W 10 W 1 W 3 W


94. Tuned voltage amplifiers are not used in
Public address system Radio Receivers
TV receivers None of these


95. A tuned collector oscillator in radio receiver has a fixed inductance of 60 µH and has to be tunable over frequency band of 400 to 1200 kHz range of the variable capacitor to be used is
29.2 to 264.0 PF 292 to 2640 PF
264 to 2900 PF 292 to 26400 PF


96. Wein bridge oscillator uses
Positive feedback
Negative feedback
Both Positive and Negative feedback
No feedback


BKU-14144-A 18
97. An Op-Amp has offset current of 100 nA and feedback resistance of 200 k.. Offset voltage is
2 mV 20 mV
200 mV .2 mV


98. Amplitude modulation is used when
Bandwidth is small Area of reception is large
Both and None of the above


99. Radio waves have frequency range from
Few Hertz to 103 Hertz Few Hertz to 106 Hertz
Few Hertz to 109 Hertz Few Hertz to 1012 Hertz


100. In superheterodyne receiver converter stage consists of
Mixer and Detector Mixer and I.F. amplifier
Mixer and Local oscillator None of these


101. Convert binary number 0.101 to decimal number
0.6 0.625
0.62 6.0


102. Subtract (101)2 from (111)2
001 010
100 101


103. In NOT circuit
Input is low output is low Input is high output is high
Input is low output is high None of these


104. Exclusive NOR circuit is represented as
X A ·B A·B X A·B A·B X X A– B



105. Fig. performs logic function of A


Fig. 105
OR XOR
NAND AND


106. In a C.R.O. of 200 50 Hz signal produces a deflection of 4 c.m. corresponding to a certain setting of vertical gain control. If another voltage produces a deflection of 5 c.m.,
what is the value of this voltage 50 V 200 V 250 V 300 V
107. Analog multimeters are Very cheap Very accurate Easy to operate None of these

108. An optical signal has lost 85% of its power after traversing 500 m of fibre. What is the loss in dB/km of this fibre
14.1 db/m 1.41 db/km
1.41 db/m 141 db/km


109. An ideal d.c. generator is one that has voltage regulation.
low zero
positive negative


110. Which of the following d.c. generator cannot be build up on open circuit
shunt series
short shunt long shunt


111. Speed of a d.c. motor can be controlled by varying
flux per pole resistance of armature
applied voltage all of the above


112. Which of the following is best suited for 3-phase 4 wire service
.-.
.­


(D)
BKU-14144-A 20
113. Main purpose of performing open circuit test on a transformer is to measure its
copper loss core loss
total loss insulation resistance


114. When a 400 Hz transformer is operated at 50 Hz its kVA is
reduced to 1/8 increased 8 times
unaffected increased 64 times


115. Efficiency of a 3 phase induction motor is approximately proportional to 1-s s (D)Ns
116. In a three-phase induction motor rotor field rotates at synchronous speed with respect to
stator rotor
stator flux none of these


117. A 6 pole, 50 Hz 3-phase induction motor has a full load speed of 950 R.P.M. At half load its speed would be r.p.m.
475 500
975 1000


118. One of the characteristics of a single phase induction motor is
Self starting Not self starting
Requires only one winding Can rotate in one direction only


119. For general time varying fields Maxwell’s equation
B.ds= 0 represents
Gauss’ Law—Magnetic Gauss’ Law
Faraday’s Law Maxwell-Ampere Law


120. Maxwell’s equation of continuity in differential form is given as
. ·D . ·B 0
.S .B


(C)
. ·J – .× E –


.t .t
ROUGH WORK

ROUGH WORK

ROUGH WORK