October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
When the current gain increases from 50 to 300 in an emitter-biased circuit, the collector current
Previous ()«
()
is zero
decreases by a factor of 6
remains almost the same
increases by a factor of 6
»Next
Add your Comment
3 hours, 59 minutes, 49 seconds.
Statistics
1
0
Correct
1.00 %
Eiciency
Wrong
99
Missed
October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
The main function of interpoles is to minimize ____ between the brushes and the commutator when the dc machine is loaded.
Previous ()«
()
current
sparking
friction
»Next
wear and tear
Add your Comment
3 hours, 59 minutes, 30 seconds.
Statistics
1
1
Correct
1.00 %
Eiciency
Wrong
98
Missed
October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
What is the differential equation for the current i (t) in the circuit of figure shown?
Previous ()«
Add your Comment
()
»Next
3 hours, 59 minutes, 17 seconds.
October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
Which of the following statements describes the basic operating principle of a magnetic amplifier?
Previous ()«
()
»Next
Any power amplifier will create a magnetic field which can be used to increase the gain of the power amplifier
A changing inductance can be used to control the current in a load
The inductance of an air-core inductor will change as the power used by the load changes
Magnetism can be increased (amplified) by changing the voltage amplitude
Add your Comment
3 hours, 59 minutes, 4 seconds.
Statistics
1
Correct
3
Wrong
October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
An inverter on the clock input has which of the following effects on the D flip flop?
Previous ()«
()
»Next
The output will change on the negative-going transition of the clock pulse
The data input will change at the clock frequency
The output will change on the positive-going transition of the clock pulse
The output will change at the clock frequency
Add your Comment
3 hours, 58 minutes, 53 seconds.
Statistics
2
Correct
3
Wrong
2.00 %
Eiciency
95
Missed
October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
A capacitor of 10 µF capacitance is allowed to discharge through its own leakage resistance and a fall of voltage from 120 V to 100 V is recorded in a time interval of 5 minutes by an electronic voltmeter connected in parallel. Calculate the leakage resistance of the capacitor.
Previous ()«
()
164.84 kΩ
164.84 GΩ
164.84 MΩ
164.84 Ω
Explanation
Add your Comment
»Next
3 hours, 58 minutes, 43 seconds.
October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
LEDs are commonly fabricated from gallium compounds like gallium arsenide and gallium phosphide because they
Previous ()«
()
»Next
emit more light
are easily available
are cheap
emit more heat
Add your Comment
3 hours, 58 minutes, 28 seconds.
Statistics
3
4
Correct
3.00 %
Eiciency
Wrong
93
Missed
October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
The current
is
Previous ()«
()
»Next
the same as
the emitter current in the common-collector connected transistor with zero base current
the collector current in the common-emitter connected transistorwith zero emitter current
the collector current in the common-emitter connected transistor with zero base current
Add your Comment
3 hours, 58 minutes, 16 seconds.
Statistics
3
Correct
5
Wrong
3.00 %
Eiciency
92
Missed
October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
In the circuit shown, the input offset voltage and the input offset current are
= 4mV and
= 150 nA. Calculate the total offset voltage.
Previous ()«
()
497 mV
479 mV
749 mV
974 mV
Explanation
»Next
October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
The reverse saturation current in a junction diode is the current that flows when ______.
Previous ()«
()
the potential barrier is zero
only majority carrier are crossing the junction
the junction is unbiased
»Next
only minority carriers are crossing the junction
Add your Comment
3 hours, 57 minutes, 58 seconds.
Statistics
3
Correct
7
Wrong
3.00 %
Eiciency
90
Missed
October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
The field-effect transistor (FET)
Previous ()«
()
has three NP-junctions
incorporates a forward-biased junction
depends on the variation of a magnetic field for its operation
»Next
depends on the variation of the depletion-layer width reverse voltage for its operation
Add your Comment
3 hours, 55 minutes, 41 seconds.
Statistics
3
Correct
8
Wrong
3.00 %
Eiciency
89
Missed
October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
If P is Passivation, Q is n-well implant, R is metallization and S is source/drain diffusion, then the order in which they are carried out in a standard n-well CMOS fabrication process, is
Previous ()«
()
P-Q-R-S
R-P-S-Q
Q-S-R-P
S-R-Q-P
»Next
Add your Comment
3 hours, 55 minutes, 30 seconds.
Statistics
3
9
Correct
3.00 %
Eiciency
Wrong
88
Missed
October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
For a given line voltage, four heating coils will produce maximum heat when connected ______.
Previous ()«
()
»Next
all in parallel
with two parallel pairs in series
one pair in parallel with the other two in series
all in series
Add your Comment
3 hours, 55 minutes, 17 seconds.
Statistics
4
9
Correct
4.00 %
E甦iciency
Wrong
87
Missed
October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
The output of a filter drops from 10 to 5 V as the frequency is increased from 1 to 2 kHz. What is the dB change in the output voltage?
Previous ()«
()
-6 dB/octave
-3 dB/octave
-3 dB/decade
6 dB/octave
»Next
Add your Comment
3 hours, 55 minutes, 8 seconds.
Statistics
5
9
Correct
5.00 %
E蓟iciency
Wrong
86
Missed
October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
The Q-point in a voltage amplifier is selected in the middle if the active region because
Previous ()«
()
the circuit then requires less number of resistor
the operating point then becomes very stable
it gives a distortion less output
»Next
it then requires a small dc voltage
Add your Comment
3 hours, 54 minutes, 54 seconds.
Statistics
5
Correct
10
Wrong
5.00 %
Eiciency
85
Missed
October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
When determining the common-emitting current gain by making small changes in direct currents, the collector voltage is held constant so that
Previous ()«
()
the transistor will not burn out
the output resistance will be high
the change in collector current will be due to a change in base current.
the changes in emitting current will be due to a change in base current.
»Next
Add your Comment
3 hours, 54 minutes, 36 seconds.
Statistics
5
11
Correct
5.00 %
Eiciency
Wrong
84
Missed
October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
Generally, the gain of a transistor amplifier falls at high frequencies due to the ____.
Previous ()«
()
internal capacitances of the device
coupling capacitor at the output
coupling capacitor at the input
»Next
skin effect
Add your Comment
3 hours, 54 minutes, 10 seconds.
Statistics
5
Correct
12
Wrong
5.00 %
Eiciency
83
Missed
October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
In a feedback series regulator circuit, the output voltage is regulated by controlling the
Previous ()«
()
reference voltage
gain of the feedback transistor
»Next
voltage drop across the series pass transistor
magnitude of input voltage
Add your Comment
3 hours, 54 minutes, 1 second.
Statistics
5
Correct
13
Wrong
5.00 %
E礔iciency
82
Missed
October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
The series field of a short-shunt dc generator is excited by ________ currents.
Previous ()«
()
external
shunt
load
»Next
armature
Add your Comment
3 hours, 53 minutes, 47 seconds.
Statistics
5
Correct
14
Wrong
5.00 %
E礔iciency
81
Missed
October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
A 0 to 6 counter consists of 3 flip flop and a combination circuit of 2 input gate (s). The common circuit consists of
Previous ()«
()
One OR gate
One AND gate
One AND gate and one OR gate
»Next
Two AND gates
Add your Comment
3 hours, 53 minutes, 35 seconds.
Statistics
5
15
Correct
5.00 %
E礔iciency
Wrong
80
Missed
October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
The input to an op-amp differentiator circuit is a sinusoidal voltage of peak value 10µV and frequency of 2 kHz. If the values of differentiating components are given as R = 40 k Ω and C = 3 µF, determine the output voltage.
Previous ()«
()
15.082(cos4000πt) µV
15.082(sin4000πt) µV
10.082(sin4000πt) µV
10.082(cos4000πt) µV
Explanation
»Next
Add your Comment
October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
The number of minority carries crossing the junction of a diode depends primarily on the
Previous ()«
()
»Next
magnitude of the potential barrier
rate of thermal generation of electron-hole pairs.
magnitude if the forward-bias voltage
concentration of doping impurities
Add your Comment
3 hours, 53 minutes, 3 seconds.
Statistics
7
Correct
15
Wrong
7.00 %
Eiciency
78
Missed
October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
What is the most useful ac bridge for comparing capacitances of two air capacitors?
Previous ()«
()
Wien series bridge
Wien parallel bridge
Schering bridge
»Next
De Sauty bridge
Add your Comment
3 hours, 52 minutes, 48 seconds.
Statistics
8
Correct
15
Wrong
8.00 %
Eiciency
77
Missed
October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
Calculate the resistance of a 2 km length of aluminum overhead power cable if the crosssectional area of the cable is
Previous ()«
. Take the resistivity of aluminum to be
()
0.3 ohm
0.5 ohm
0.4 ohm
0.6 ohm
Explanation
Add your Comment
.
»Next
3 hours, 52 minutes, 36 seconds.
October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
One advantage of a class B push-pull amplifier is _____. 1. Very small quiescent current drain 2. Maximum efficiency of 78.5 % 3. Greater efficiency than class A
Previous ()«
()
1, 2 and 3
2 and 3
1 and 2
1 and 3
Add your Comment
3 hours, 52 minutes, 23 seconds.
»Next
Statistics
9
Correct
16
Wrong
October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
Match items in Group 1 with items in Group 2, most suitably.
Previous ()«
()
P – 3, Q - 4, R - 1, S – 2
P - 2, Q - 3, R - 1, S - 4
P - 2, Q - 1, R - 4, S - 3
P - 1, Q - 2, R - 4, S - 3
Add your Comment
3 hours, 51 minutes, 57 seconds.
»Next
Statistics
9
Correct
17
Wrong
October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
By packing data within an 8-bit code, which of the following results are achieved?
Previous ()«
()
Storage space required decreases and processing speed increases
Storage space required increases and processing speed increases
Storage space required increases and processing speed decreases
Storage space required decreases and processing speed decreases
»Next
Add your Comment
3 hours, 51 minutes, 43 seconds.
Statistics
10
Correct
17
Wrong
10.00 %
E礔iciency
73
Missed
October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
Surface-leakage current is part of the _______.
Previous ()«
()
forward current
reverse current
reverse breakdown current
forward breakdown current
»Next
Add your Comment
3 hours, 51 minutes, 27 seconds.
Statistics
10
Correct
18
Wrong
10.00 %
Eiciency
72
Missed
October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
The forward bias applies to a PN-junction diode is increased from zero to higher values. Rapid increase in the current flow relatively small increase in voltage occurs _____.
Previous ()«
()
»Next
when the depletion area becomes larger than the space-charge area.
when the flow of minority carriers is sufficient to cause an avalanche breakdown
only after the forward bias exceeds the potential barrier.
immediately
Add your Comment
3 hours, 51 minutes, 15 seconds.
Statistics
10
Correct
19
Wrong
10.00 %
Eiciency
71
Missed
October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
The circuit shown is an emitter-follower amplifier with voltage divider bias AC equivalent circuit. Calculate the voltage gain if
Previous ()«
()
0.989
0.889
0.978
0.998
Explanation
»Next
Add your Comment
3 hours, 51 minutes, 1 second.
Statistics
11
Correct
11.00 %
E㼑iciency
19
Wrong
70
Missed
Challenge friends... Search your friends & hit enter...
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Previous ()«
How others answered this?
()
»Next
October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
In a semiconductor diode, the barrier potential offers opposition to only
Previous ()«
()
minority carriers in both regions
free electrons in the N-region
»Next
majority carriers in both regions
holes in the P-region
Add your Comment
3 hours, 50 minutes, 49 seconds.
Statistics
11
Correct
20
Wrong
11.00 %
Eiciency
69
Missed
October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
A 100 µF capacitor is required in fabricating an electronic circuit. Such a large value of capacitance is possible if the capacitor is a/an
Previous ()«
()
»Next
Electrolytic capacitor
Ceramic capacitor
Mica capacitor
Air-gang capacitor
Add your Comment
3 hours, 50 minutes, 38 seconds.
Statistics
12
20
Correct
12.00 %
E蘓iciency
Wrong
68
Missed
October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
A regulated power supply, shown in the figure, has an unregulated input (UR) of 15 volts and generates a regulated output
. If the unregulated voltage increases by 20%, then the power
dissipation across the transistor Q1
Previous ()«
()
increases by 20%
remains unchanged
increases by 50%
decreases by 20%
Explanation
»Next
Add your Comment
3 hours, 50 minutes, 23 seconds.
Statistics
12
Correct
% 12.00
21
Wrong
67
October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
Doping materials are called impurities because they
Previous ()«
()
decrease the number of charge carriers
make semiconductors less than 100 percent pure
»Next
alter the crystal structures of the pure semiconductors
change the chemical properties of semiconductors
Add your Comment
3 hours, 50 minutes, 10 seconds.
Statistics
12
Correct
22
Wrong
12.00 %
Eiciency
66
Missed
October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
If in the case of a certain dc armature, the number of commutator segments is found either one less or more than the number of slots, the armature must be having a simplex ______ winding.
Previous ()«
()
lap
wave
frog leg
»Next
multielement
Add your Comment
3 hours, 49 minutes, 59 seconds.
Statistics
12
23
Correct
12.00 %
Eiciency
Wrong
65
Missed
October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
The circuit shown in Figure 12 converts ________.
Previous ()«
()
Excess – 3 to gray code
Binary to excess – 3 code
Gray to Binary Code
BCD to binary code
»Next
Add your Comment
3 hours, 49 minutes, 42 seconds.
Statistics
12
Correct
24
Wrong
12.00 %
Eiciency
64
Missed
October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
For the BJT,
in the circuit shown,
t=0, the switch is opened. At what time t
Previous ()«
. The switch is initially closed. At time leaves the active region?
()
10 ms
50 ms
100 ms
25 ms
Explanation
»Next
October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
In a PN-junction diode, if the junction current is zero, this means that
Previous ()«
()
»Next
the number of majority carriers crossing the junction equals the number of minority carriers crossing the junction
the potential barrier has disappeared
the number of holes diffusing from the P-region equals the number of electrons diffusing from the N-region.
there are no carriers crossing the junction
Add your Comment
3 hours, 48 minutes, 52 seconds.
Statistics
14
26
Correct
14.00 %
Wrong
60
October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
The light-emitting diode (LED)
Previous ()«
()
gives a light output which increases with increase in temperature
is usually made from silicon
»Next
uses a reverse-biased junction
depends on the recombination of holes and electrons
Add your Comment
3 hours, 48 minutes, 40 seconds.
Statistics
14
Correct
27
Wrong
14.00 %
E礔iciency
59
Missed
October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
If the base resistor is very small, the transistor will operate in the _____ region.
Previous ()«
()
breakdown
cutoff
»Next
saturation
active
Add your Comment
3 hours, 48 minutes, 30 seconds.
Statistics
14
Correct
28
Wrong
14.00 %
E礔iciency
58
Missed
October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
The frequency of the system with which several alternators are paralleled can be increased by simultaneously _________ of all generators.
Previous ()«
()
decreasing the field excitation
decreasing the speed of prime movers
increasing the field excitation
»Next
increasing the speed of prime movers
Add your Comment
3 hours, 47 minutes, 33 seconds.
Statistics
14
29
Correct
14.00 %
Eiciency
Wrong
57
Missed
October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
Match items in Group 1 with items in Group 2, most suitably. Group 1
Group 2
P. LEAD
1.Heavy doping
Q. Avalanche photo diode
2. Coherent radiation
R. Tunnel diode
3. Spontaneous emission
S. LASER
4. Current gain
Previous ()«
()
P - 3 Q - 4, R - 1, S – 2
P - 2, Q - 3, R - 1, S – 4
P - 2, Q - 1, R - 4, S – 3
P - 1, Q - 2, R - 4, S – 3
Add your Comment
»Next
October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
How is the output connected as shown in the figure? And choose what type of circuit is shown below.
Previous ()«
()
»Next
Any of the above could be correct, depending on the specific application involved.
It is an open-collector gate and is used to drive loads that cannot be connected directly to Vcc due to high noise levels.
It represents an active-LOW ni verter and is used in negative logic systems.
It is an open-collector gate. An external load must be connected between the output terminal and appropriate supply voltage.
Add your Comment
October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
In a PN-junction diode, holes diffuse from the P-region to the N-region because
Previous ()«
()
»Next
there is greater concentration of holes in the P-region as compared to N-region
they are swept across the junction by the potential difference
the free electrons in the N-region attract them
none of the above
Add your Comment
3 hours, 46 minutes, 58 seconds.
Statistics
16
Correct
30
Wrong
16.00 %
Eiciency
54
Missed
October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
The DTL, TTL, ECL and CMOS family of digital ICs are compared in the following 4 columns:
What is the correct column?
Previous ()«
()
R
P
Q
S
Add your Comment
»Next
3 hours, 46 minutes, 46 seconds.
October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
In an 8085 microprocessor, the instruction CMP B has been executed while the content of the accumulator is less than that of register B. As a result
Previous ()«
()
»Next
Carry flag will be set but Zero flag will be reset
Both Carry flag and Zero flag will be set
Carry flag will be rest but Zero flag will be set
Both Carry flag and Zero flag will be rest
Add your Comment
3 hours, 46 minutes, 36 seconds.
Statistics
17
31
Correct
17.00 %
Eiciency
Wrong
52
Missed
October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
Thyristor T shown is initially off and is triggered with a single pulse of width 10 µs. It is given that L=100/π µH and C = 100/π µF. Assuming latching and holding currents of the thyristor are both zero and the initial charge on C is zero, T conducts for ____.
Previous ()«
()
100 µs
50 µs
200 µs
10 µs
Explanation
»Next
October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
For an n−channel enhancement type MOSFET, if the source is connected at a higher potential than that of the bulk (i.e. V 0 > SB), the threshold voltage
Previous ()«
()
»Next
change polarity
increase
decrease
of the MOSFET will
remain unchanged
Add your Comment
3 hours, 46 minutes, 12 seconds.
Statistics
19
31
Correct
19.00 %
Eiciency
Wrong
50
Missed
October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
What, if anything, can happen to a floppy disk when it is exposed to direct sunlight or excessive heat?
Previous ()«
()
»Next
It can become warped or distorted so it cannot be used
It can lose part of the data recorded on it
Nothing, it is not affected
It can become sticky, which stops the drive
Add your Comment
3 hours, 45 minutes, 22 seconds.
Statistics
20
31
Correct
20.00 %
Eiciency
Wrong
49
Missed
October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
What is the impedance looking into nodes 1 and 2 in the given circuit as shown in the figure?
Previous ()«
()
100 Ω
50 Ω
10.1k Ω
5k Ω
Explanation
»Next
Add your Comment
3 hours, 45 minutes, 10 seconds.
Statistics
Challenge friends...
20
Correct
20.00 %
E琇iciency
32
Wrong
48
Missed
Search your friends & hit enter...
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October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
When a PN- junction is biased in the forward direction
Previous ()«
()
Only electrons in the N-region are injected into the P-region.
Only holes in the P-region are injected into the N-region.
Majority carriers in each region are injected into the region.
»Next
No carriers move.
Add your Comment
3 hours, 44 minutes, 58 seconds.
Statistics
20
Correct
33
Wrong
20.00 %
Eiciency
47
Missed
October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
When the gate-to-source voltage
of a MOSFET with threshold voltage of 400 mV,
working in saturation is 900 mV, the drain current is observed to be 1 mA. Neglecting the channel width modulation effect and assuming that the MOSFET is operating at saturation, what is the drain current for an applied Previous ()«
of 1400 mV? ()
2.0 mA
3.5 mA
0.5 mA
4.0 mA
Explanation
Add your Comment
»Next
October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
An SCR circuit operates from 300V DC supply, has series inductance of 4 µH. A resistance of 4Ω and capacitance of 0.2 µF is connected across the SCR. Calculate the safe dv/dt and di/dt ratings of SCR.
Previous ()«
()
75 A/µs; 133.76 V/µs
57 A/µs; 133.76 V/µs
57 A/µs; 137.36 V/µs
75 A/µs; 137.36 V/µs
Explanation
»Next
Add your Comment
3 hours, 44 minutes, 36 seconds.
Statistics
21
Correct
21.00 %
E䥛iciency
34
Wrong
45
Missed
Challenge friends...
Search your friends & hit enter...
What's your message? (optional)
Previous ()«
How others answered this?
()
»Next
October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
The extremely high input impedance of a MOSFET is primarily due to the
Previous ()«
()
depletion of current carriers
absence of its channel
»Next
extremely small leakage current of its gate capacitor
negative gate-source voltage
Add your Comment
3 hours, 44 minutes, 25 seconds.
Statistics
21
Correct
35
Wrong
21.00 %
E礔iciency
44
Missed
October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
The source if a silicon depth of
n-channel MOS transistor has an area of
. If the dopant density in the source is
, what is approximately the number
of holes in the source region with the above volume?
Previous ()«
()
100
10
0
Explanation
and a
»Next
October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
A transistor connected in common-base configuration has
Previous ()«
()
a low input resistance and high output resistance
a low input resistance and low output resistance
a high input resistance and low output resistance
a high input resistance and a high output resistance
»Next
Add your Comment
3 hours, 43 minutes, 38 seconds.
Statistics
22
Correct
36
Wrong
22.00 %
E礔iciency
42
Missed
October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
A flux density of 1.2 T is produced in a piece of cast steel by a magnetizing force of 1250 A/m. Find the relative permeability of the steel under these conditions.
Previous ()«
()
764
745
746
754
Explanation
Add your Comment
»Next
3 hours, 43 minutes, 28 seconds.
October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
The rms value of a half-wave rectified current is 10A, its value for full-wave rectification would be _____ amperes.
Previous ()«
()
20/π
14.14
20
40/π
»Next
Add your Comment
3 hours, 43 minutes, 20 seconds.
Statistics
23
37
Correct
23.00 %
Eiciency
Wrong
40
Missed
October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
The oscillator circuit shown in the figure has an ideal inverting amplifier. What is its frequency of oscillation (in Hz)?
Previous ()«
Add your Comment
()
»Next
October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
A source of angular frequency 1 rad/sec has a source impedance consisting of 1 Ω resistance in series with 1 H inductance. The load that will obtain the maximum power transfer is
Previous ()«
()
»Next
1 Ω resistance in parallel with 1 H inductance
1 Ω resistance in series with 1 F capacitor
1 Ω resistance in parallel with 1 F capacitor
1 Ω resistance
Add your Comment
3 hours, 42 minutes, 34 seconds.
Statistics
23
39
Correct
23.00 %
Eiciency
Wrong
38
Missed
October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
The sole purpose of a commutator in a dc generator is to __.
Previous ()«
()
increase output voltage
provide smoother output
»Next
convert the induced ac into dc
reduce sparking at brushes
Add your Comment
3 hours, 42 minutes, 24 seconds.
Statistics
23
Correct
40
Wrong
23.00 %
E礔iciency
37
Missed
October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
Hay’s bridge is particularly useful for measuring _____.
Previous ()«
()
»Next
capacitance and dielectric loss
inductive impedance with large phase angle
mutual inductance
self inductance
Add your Comment
3 hours, 42 minutes, 13 seconds.
Statistics
23
Correct
41
Wrong
23.00 %
E礔iciency
36
Missed
October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
Trickle charging of a storage battery helps to ____.
Previous ()«
()
increase its reserve capacity
prevent sulphation
keeps it fresh and fully charged
maintain proper electrolyte level
»Next
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3 hours, 41 minutes, 54 seconds.
Statistics
23
Correct
42
Wrong
23.00 %
Eiciency
35
Missed
October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
Shunt generators are most suited for stable parallel operation because of their ____ voltage characteristics.
Previous ()«
()
identical
dropping
linear
rising
»Next
Add your Comment
3 hours, 41 minutes, 42 seconds.
Statistics
23
43
Correct
23.00 %
Eiciency
Wrong
34
Missed
October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
With 10 V dc connected at port A in the linear nonreciprocal two-port network shown below, the following were observe: (i) 1Ωconnected at port B draws a current of 3A (ii) 2.5Ωconnected at port B draws a current of 2A With 10 V dc connected at port A, what is the current drawn by 7Ω connected at port B?
Previous ()«
()
9/7 A
1A
3/7A
5/7A
Explanation
»Next
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October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
Sulphation in a lead-acid battery occur due to ____ charging.
Previous ()«
()
»Next
trickle
incomplete
fast
heavy
Add your Comment
3 hours, 41 minutes, 12 seconds.
Statistics
23
Correct
45
Wrong
23.00 %
Eiciency
32
Missed
October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
Which is the wrong statement? The magnetizing force at the center of a circular coil varies
Previous ()«
()
directly as its radius
directly as the current
inversely as its radius
»Next
directly as the number of its turns
Add your Comment
3 hours, 41 minutes, 0 seconds.
Statistics
23
Correct
46
Wrong
23.00 %
Eiciency
31
Missed
October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
There are no transients in pure resistive circuits because they
Previous ()«
()
obey Ohm’s law
offer high resistance
are linear circuits
»Next
have no stored energy
Add your Comment
3 hours, 40 minutes, 50 seconds.
Statistics
23
Correct
47
Wrong
23.00 %
Eiciency
30
Missed
October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
An SCR has a di/dt = 120 A/µs and a dv/dt of 300 V/µs. It operates on a 250 V DC source with a load resistance of 10 Ω. Find the suitable values of inductance and capacitance of the snubber circuit.
Previous ()«
()
2.8 µH; 0.053 µF
2.8 µH; 0.53 µF
2.08 µH; 0.53 µF
2.08 µH; 0.053 µF
Explanation
»Next
October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
Choose proper substitutes for X and Y to make the following statements correct. Tunnel diode and Avalanche photodiode are operated in X bias and Y bias respectively.
Previous ()«
()
X : reverse, : reverse, Y: reverse
X : reverse, : reverse, Y: forward
X : forward, : reverse, Y: forward
X : forward, : reverse, Y: reverse
»Next
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3 hours, 40 minutes, 22 seconds.
Statistics
23
49
Correct
23.00 %
Eiciency
Wrong
28
Missed
October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
Circuit shown is the common-base amplifier with voltage divider bias AC equivalent circuit. Calculate the input resistance if
Previous ()«
.
()
23.6 Ω
63.2 Ω
62.3 Ω
26.3 Ω
Explanation
»Next
Add your Comment
3 hours, 40 minutes, 8 seconds.
Statistics
24
Correct
24.00 %
E謌iciency
49
Wrong
27
Missed
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()
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October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
After
reaches pinch-off value
in a JFET, drain current
Previous ()«
()
low
reversed
zero
becomes
»Next
saturated
Add your Comment
3 hours, 39 minutes, 57 seconds.
Statistics
24
Correct
50
Wrong
24.00 %
Eiciency
26
Missed
October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
A single phase fully controlled bridge converter supplies a load drawing constant and ripple free load current, if the triggering angle is 30 degrees, what will be the input power factor?
Previous ()«
()
0.85
0.78
0.65
0.866
Explanation
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October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
As compared to constant-current system, the constant-voltage system of charging a lead-acid cell has the advantage of ___.
Previous ()«
()
»Next
Both reducing time of charging and increasing cell capacity
increasing cell capacity
avoiding excessive gassing
reducing time of charging
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3 hours, 39 minutes, 6 seconds.
Statistics
25
51
Correct
25.00 %
Eiciency
Wrong
24
Missed
October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
In a meter movement, shunt strips with a zero temperature coefficient are used instead of regular carbon resistance for which of the following reasons?
Previous ()«
()
»Next
Because regular carbon resistances are not able to handle the current changes
Because regular carbon resistances cause interfering magnetic fields
Because regular carbon resistances are affected by heat due to current and cause readings to vary
Because regular carbon resistances are too large to be used
Add your Comment
3 hours, 38 minutes, 47 seconds.
Statistics
25
52
Correct
% 25.00
Wrong
23
October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
The collector voltage of a Class B push pull amplifier with
= 40 Volts swings down to a
minimum of 4 volts. The total power dissipation in both the transistors is 36 watts. Compute the total dc power input.
Previous ()«
()
121.67 W
128.25 W
122.85 W
125.28 W
Explanation
»Next
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October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
In a PNP transistor with normal bias
Previous ()«
()
the collector junction has a low resistance
only majority carriers cross the collector junction
only holes cross the collector junction
»Next
the emitter-base junction is forward-biased and the collector-base junction is reversebiased
Add your Comment
3 hours, 38 minutes, 16 seconds.
Statistics
25
Correct
54
Wrong
25.00 %
Eiciency
21
Missed
October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
For an n−channel enhancement type MOSFET, if the source is connected at a higher potential than that of the bulk (i.e. VSB > 0), the threshold voltage
Previous ()«
of the MOSFET will ___.
()
decrease
increase
remain unchanged
change polarity
»Next
Add your Comment
3 hours, 38 minutes, 7 seconds.
Statistics
25
55
Correct
25.00 %
Eiciency
Wrong
20
Missed
October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
In a low-pass filter, the cutoff frequency is represented by the point where the output voltage is reduced to _____ percent of the input voltage.
Previous ()«
()
33.3
50
63.2
70.7
»Next
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3 hours, 37 minutes, 54 seconds.
Statistics
25
56
Correct
25.00 %
Eiciency
Wrong
19
Missed
October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
A closed magnetic circuit of cast steel contains a 6 cm long path of cross-sectional area 1 cm^2 and a 2 cm path of cross-sectional area
. A coil of 200 turns is wound around the 6 cm
length of the circuit and a current of 0.4 A flows. Determine the flux density in the 2 cm path, if the relative permeability of the cast steel is 750. Previous ()«
()
1.31 T
1.61 T
1.41 T
1.51 T
Explanation
»Next
Add your Comment
3 hours, 37 minutes, 40 seconds.
Statistics
25
Correct
25.00 %
E⠻iciency
57
Wrong
18
Missed
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()
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October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
The output of the 74 series of TTL gates is taken from a BJT in
Previous ()«
()
Common collector configuration
Totem pole and common collector configuration
Common base configuration
»Next
Either totem pole or open collector configuration
Add your Comment
3 hours, 37 minutes, 28 seconds.
Statistics
25
Correct
58
Wrong
25.00 %
Eiciency
17
Missed
October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
The
through the base of a silicon NPN transistor is 1 + 0.1 cos
K,
mA. At 300
in the small signal model of the transistor is _____.
Previous ()«
()
25 Ω
27.5Ω
250 Ω
22.5 Ω
Explanation
»Next
October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
Three different Q points are shown on a load line. The upper Q point represents the ______.
Previous ()«
()
»Next
maximum current gain
cutoff point
minimum current gain
intermediate current gain
Add your Comment
3 hours, 37 minutes, 10 seconds.
Statistics
26
Correct
59
Wrong
26.00 %
Eiciency
15
Missed
October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
What is the average power delivered to an impedance (4 - j3) Ω by a current 5 cos (100πt + 100) A?
Previous ()«
()
62.5 W
125 W
50 W
44.2 W
Explanation
»Next
October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
In a JFET, as external bias applied to the gate is increased
Previous ()«
()
channel resistance is decreased
drain current is increased
»Next
pinch-off voltage is reached at lower values of ID
size of depletion regions is reduced.
Add your Comment
3 hours, 36 minutes, 52 seconds.
Statistics
26
Correct
61
Wrong
26.00 %
Eiciency
13
Missed
October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
Electrical contact materials used in switches, brushes, relay must possess
Previous ()«
()
low thermal conductivity and low melting point
high thermal conductivity and low melting point
high thermal conductivity and high melting point
low thermal conductivity and high melting point
»Next
Add your Comment
3 hours, 36 minutes, 37 seconds.
Statistics
26
Correct
62
Wrong
26.00 %
Eiciency
12
Missed
October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
The voltage at the terminals of a battery is 52 V when no load is connected and 48.8 V when a load taking 80 A is connected. Find the internal resistance of the battery. What would be the terminal voltage when a load taking 20 A is connected?
Previous ()«
()
52.1 V
51.2V
49.5 V
45.9 V
Explanation
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October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
Determine the reluctance of a piece of mumetal of length 150 mm and cross-sectional area 1800 mm^2 when the relative permeability is 4000. Find also the absolute permeability of the mumetal.
Previous ()«
()
16580
16850
15680
18650
Explanation
»Next
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October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
The action of JFET in its equivalent circuit can best be represented as a
Previous ()«
()
Current controlled voltage source
Voltage controlled voltage source
Voltage controlled current source
Current controlled current source
»Next
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3 hours, 35 minutes, 35 seconds.
Statistics
28
Correct
63
Wrong
28.00 %
Eiciency
9
Missed
October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
Diffusion of free electrons across the junction of an unbiased diode produces which of the following?
Previous ()«
()
»Next
Reverse bias
Depletion layer
Breakdown
Forward bias
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3 hours, 35 minutes, 26 seconds.
Statistics
28
64
Correct
28.00 %
E礔iciency
Wrong
8
Missed
October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
In an intrinsic semiconductor, the number of free electrons
Previous ()«
()
is less than the number of holes
has no relation to number of holes
»Next
equals the number of holes
is greater than the number of holes
Add your Comment
3 hours, 35 minutes, 17 seconds.
Statistics
28
Correct
65
Wrong
28.00 %
E禵iciency
7
Missed
October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
A regulated power supply, shown in the figure below, has an unregulated input (UR) of 15 volts and generates a regulated output
What is the power dissipation across the transistor
Q1?
Previous ()«
()
6.0 watts
6.0 watts
5.4 watts
4.8 watts
Explanation
»Next
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3 hours, 35 minutes, 6 seconds.
Statistics
28
Correct
28.00 %
E
iciency
66
Wrong
6
Missed
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()
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October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
Choose the correct match for input resistance of various amplifier configurations shown below:
Previous ()«
()
CB -MO, CC-HI, CE-LO
CB -LO, CC-HI, CE-MO
CB- LO, CC-MO, CE-HI
CB -HI, CC-LO, CE-MO
Add your Comment
3 hours, 34 minutes, 55 seconds.
Statistics
»Next
28
Correct
%28.00
67
Wrong
5
October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
A transformer designed for a low frequency will NOT be damaged when used at higher frequencies. What change within the transformer, limits transformer current to a safe value at higher frequencies?
Previous ()«
()
Increased hysteresis loss
Increased leakage flux
»Next
Increased inductive reactance
Increased eddy-current loss
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3 hours, 34 minutes, 45 seconds.
Statistics
28
68
Correct
%28.00
Wrong
4
October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
The operating point of an NPN transistor amplifier should not be selected in the saturation region as
Previous ()«
()
»Next
it may require high dc collector supply.
it may drive the transistor to thermal runaway
it may cause output to be clipped in the negative half of the input signal
it may cause output to be clipped in the positive half of the input signal
Add your Comment
3 hours, 34 minutes, 36 seconds.
Statistics
28
69
Correct
28.00 %
E
iciency
Wrong
3
Missed
October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
The input offset current equals the
Previous ()«
()
difference between two base-emitter voltages
average of two base currents
collector current divided by current gain
»Next
difference between two base currents
Add your Comment
3 hours, 34 minutes, 27 seconds.
Statistics
28
Correct
70
Wrong
28.00 %
Eiciency
2
Missed
October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
If a 75-ohm sample of copper wire at 0ºC is heated to 30ºC, what is the approximate total resistance? (The temperature coefficient of resistance of copper at 0ºC is 0.00427).
Previous ()«
()
84.61 degrees
86.41 degrees
85.21 degrees
81.64 degrees
Explanation
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3 hours, 34 minutes, 12 seconds.
Statistics
October 2016 Pre-Board Examination ELECTRONICS ENGINEERING
What best describes the circuit shown in Figure 6?
Previous ()«
()
A voltage doubler
A ring modulator
A bridge rectifier
A frequency discriminator
»Next
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3 hours, 34 minutes, 7 seconds.
Statistics
30
Correct
70
Wrong
30.00 %
Eiciency
0
Missed