AM Electronics (march 2020) b) 

     negative feedback 6. The master slave JK flip-flop is

effectively a combination of?
1. Carrier frequency 100 kHz and c)      partly positive and partly negative
modulated signal frequency 5 kHz what feedback a)      A T flip-flop and a D flip-flop
is bandwidth of AM?
b)      An SR flip-flop and a D flip-flop
d)      neither positive nor negative feedback
a)      100khz
c)       An SR flip-flop and a T flip-flop
 
b)      105khz
d)      Two T flip-flops
4. In a rectifier, larger the value of
c)       5khz shunt capacitor filter; e)      None of the above
d)      10khz     a)      larger the p-p value of ripple voltage  
Explanation:  bandwidth= 2Fm (max) = 2(5 kHz) = b)      larger the peak current in the rectifying
10 kHz 7.  What is the expected modulation
diode
index in case of wide band FM?
  c)       longer the time that current pulse flows
through the diode
2. What do the content of the stack a)      less than 1
pointer specify?  d)      smaller the dc voltage across the load
b)       1
a)      Address of the top of stack  
c)        1⁄2
b)      Address of bottom of stack 5. A single transistor can be used to build
which of the following digital logic gates? d)       more than 1
c)       Content of the top of stack
a)      AND
d)      content of the bottom of stack 
b)      NAND 8. Two important characteristics of
  CMOS devices are ____________.
c)       NOT
3. An Oscillator produces oscillations due
to: d)      OR a)      High noise immunity

a)      positive feedback   b)      Low static power consumption

 c)       High resistivity Explanation: Ohm’s law for magnetic 13. Resistance of material depends
circuits states that the MMF is directly on?
d)      Both high noise immunity and proportional to the magnetic flux where
low static power consumption reluctance is the constant of a)      Area    
proportionality.mmf=Flux*Reluctance
b)      Length  

9. The main difference between a c)       Type of material   

register and a counter is ___________. 11. Which of the following is the fastest
switching device? d)      All
a)           a)    A register has no specific
sequence of states  
a)      JEFT
b)           b)   A counter has no specific sequence 14. A loop antenna is a commonly used
of states for?
b)      Triode

c)            c)   A register has capability to store

c)        MOSFET
one bit of information but counter has n-bit a)      radar
d)       BJT
d)           d)   A register counts data b)      direction finding
 
c)       satellite communication
12. ___________ has tendency to
10. Ohm’s law for magnetic circuits is oscillate. d)      all of the above
_________
a)      Close loop system  

a)      F=ϕS b)      Open loop system  15. A better SNR can be obtained in a

PCM by, 
b)       F=ϕ/S c)       Both (a) and (b)
a)      increasing sampling rate above Nyquist
c)       F=ϕ2S d)      Neither (a) or (b) rate

d)      F=ϕ/S2   b)      decreasing the code bits

c)       reducing channel bandwidth

d)      increasing quantization levels device that combines the characteristic 21. An Op-Amp comparator circuit
of BJT and MOSFET is? employs?
 
a)      IGBT a)      no feedback
16. Capacitor bank is used for the
improvement of?  b)      FCT b)      +ve feedback

Ans: Power Factor c)       MCT c)       -ve feedback

Explanation: Improving power d)      GTO d)      Both (b) and (c)

factor means reducing the phase
difference between voltage and    
current. Since the majority of loads are
of inductive nature, they require some 19. For type 1 system with parabolic 22. RC snubber circuit is used to limit
amount of reactive power for them to input, the steady state error is?  the rate of?
function. Capacitor banks reduce the
phase difference between the voltage a)      Finite constant 1. Rise of current in SCR
and current. 2. Rise of voltage across SCR
b)      Infinite
3. Conduction period
c)       zero 4. All of the above 
17. Turn on time of an SCR can be
reduced by using a,    23. In PCM system, output S/N
increases ________.
a)      Triangular pulses 20. Relaxation oscillators are used to
generate?
b)      Trapezoidal pulses
a)      Sinusoidal wave  a) parabolically with bandwidth
c)       Rectangular pulses of high amplitude
and narrow width b)      Triangular wave  b) exponentially with bandwidth (not
sure)
d)      Rectangular pulses of low amplitude and c)       Saw tooth wave 
wide width c) inversely with bandwidth
d)      Both B and C (non-sinusoidal)
d) linearly with bandwidth
18.  A modern power semiconductor  
   c)       Band stop filter }

 24. An ideal voltmeter has d)      Band pass filter  

______equivalent resistance and ideal
ammeter has _____equivalent   a)      out = 0 1 2 3 4
resistance.
27. The instructions like MOV or ADD are b)      out = 1 2 3 4 5
a)       Unity, Unity called as ___________.
c)       out = 5
b)       Zero, infinite a)      Op code
d)      out = 4
c)       Infinite, Zero b)      Operators
 
d)      Zero, Zero c)       Commands
29. In a frequency counter, what
d)      None of above
happens at high frequencies when the
sampling interval is too long?
25. CPU does not perform the  
operation? a)      The counter works fine
28. Output of the following program?
a)      data transfer b)      The counter undercounts the frequency

b)      logic operation c)       The measurement is less precise

#include<stdio.h>
c)       arithmetic operation d)      The counter overflows
Int main()
d)      all of the above  
{
  30. When transistors are used in digital
     int i=0; circuits they usually operate in the:
26. An RC differentiator acts as a
     for(i=0; i<5; i++); a)      active region
a)      Low pass filter
            cout<<”out =”<<i; b)      breakdown region
b)      High pass filter
     return 0; c)       saturation and cutoff regions
d)      linear region a)      Peak 36. Avalanche breakdown occurs at? 

  b)      RMS a)      Knee voltage

31. In a generic microprocessor instruction c)       Average b)      Breakdown voltage

cycle time is,
d)      Instantaneous  
Shorter than machine cycle 37. The forward voltage drop across a
  silicon diode is about? 
Larger than machine cycle time  (not
 
sure) a)      2.5 V
34. Voltage multipliers are circuits best
used to produce?
b)      3 V
Ten times the machine cycle time
a)      low voltage and low current
c)       10 V
 Exactly the same as the machine cycle
time b)      low voltage and high current
d)      0.7 V

  c)       high voltage and low current

 AM Electrical (may 2019)

32. _______ is less dependent on the d)      high voltage and high current 1. A power amplifier has a gain of 20
transistor beta dB and an input level of 2 volts.
Assuming that the input and output
impedances are the same, what is the
35. The Process in which A.C is voltage level at the amplifier output?
a)      Fixed Bias converted into D.C is called?
a)      10
b)      Emitter Bias a)      Induction
b)      20
c)       Voltage Divider b)      Rectification
c)       30
d)      Voltage feedback c)       Dispersion

 
d)      40
d)      Inversion
 
33. Multimeter typically provides  
measurements of __________ values.
 2. For a perfectly matched transmission 4. Often a common-collector will be the b)      Zero order hold (ZOH)
line, the voltage standing wave ratio is, last stage before the load; the main
function(s) of this stage is to: c)       RLC circuit
a)      Unity
a)      provide voltage gain d)      All of the above
b)      Zero
b)      provide phase inversion  
c)       Maximum
c)       provide a high-frequency path to 7. Which loss in transformer varies
d)      minimum  improve the frequency response significantly with load?

Explanation: d)      buffer the voltage amplifiers from a)      Hysteresis loss 

the low-resistance load and provide
The voltage standing wave ratio, VSWR is impedance matching for maximum b)      eddy current loss  
defined as the ratio of the maximum to power transfer
minimum voltage on a loss-less line. The c)       copper loss  
resulting ratio is normally expressed as
a ratio, e.g. 2:1, 5:1, etc. A perfect match is 5. 1 db corresponds to ___________ d)      core loss
1:1 and a complete mismatch, i.e. a short change in voltage or current level.
or open circuit is ∞:1.  
    a)      40%
8. The power factor of an induction motor
b)      25% operating at no load
3. A PLL maintains lock by comparing
c)       20% a)      0.2 lag
a)        the phase of two signal
d)      80% b)      0.2 lead
b)      the frequency of two signals
  c)       0.9 lag
c)       the amplitude of two signals
6. A Hold circuit when used in conjunction d)      0.9 lead
  with high sampling rate provides
satisfactory performance.   Which one? Explanation:
a)      First order hold
 The power factor of induction 11. A crack in magnetic path of an  
motors varies with load, typically from induction motor result in
around 0.85 or 0.90 at full load to as low as 14. Which of the following are ill suited
about 0.20 at no-load, due to stator and a)      unchanged inductance for energy efficient motors applications?
rotor leakage and magnetizing reactance.
b)      reduced inductance a)      Pumps
 
c)       increased inductance b)      Fans
9. ___________ relays are used for phase
faults on long line. d)      zero inductance c)       Punch presses

a)      Impedance   d)      All of the above

b)      Reactance 12. Among the series and shunt generators,  

which generator has the better regulation?
c)       Either of the above 15. To get the thevenin resistor you
a)      Series generator have to,
d)      None of the above
b)      Shunt generator a)      open the load resistor
 
    c)       Both have identical regulation. b)      short the load resistor
10. Which of the following needs to be
measured after rewinding of motor?   c)       short the voltage sources

a)      No load current 13. With the same secondary voltage and d)      open the voltage sources
filter, which has the most ripple?
b)      winding resistance  
a)      Half-wave rectifier
c)       air gap 16. The supply voltage to an induction
b)      Full-wave rectifier motor is reduced by 10%. By what
d)      all the above percentage, approximately, will the
c)       Bridge rectifier maximum torque decrease?
 
d)      Impossible to say a)      38%
 b)      19% 18. A certain appliance uses 350 W. If it is 600 s is applied to an integrator consisting
allowed to run continuously for 24 days, of a 150 kilo ohm resistor and a 0.002 F
c)       9.5% how many kilowatt-hours of energy does it capacitor. To what voltage will the
consume? capacitor charge?
d)      No change
a)      20.16 kWh a)      8.18 V
 Explanation:
b)      201.6 kWh b)      6.18 V
2
Torque α V
c)       2.01 kWh c)       5.18 V
When supply voltage reduces by 10%, it
becomes 0.9 times, therefore torque d)      8.4 kWh d)      7.18 V
becomes 0.9^2 times i.e. 0.81 times i.e.
19% less. Hence we can say that 10% Explanation: Explanation:
change in supply voltage results in 20%
change in torque. Kwh = (350*24*24)/1000 = 201.6kWh tc = RC = 150x10^3 x 0.002 = 300
Vc = Vs[1-e^-t/tc]
    Vc = 6[1-e^-600/300]
Vc = 6[1-e^-2]
17. An induction motor has synchronous 19. A 2-hp 220-V rms single phase Vc = 5.18 volts
speed of 1500 rpm. What will be the slip induction motor operates at full load with
when it is running at a speed of 1450 80 percent efficiency and 0.75 lagging  
rpm? power factor. The magnitude of RMS
motor current is most nearly: 21. The ratio sqrt(L/C) has the dimensions
a)      +3.33% of
a)      4.07 A
b)      -3.33% a)      Resistance
b)      11.3 A
c)       +3% b)      voltage
c)       6.35 A
d)      -3% c)       current
d)      8.78 A
d)      frequency

         20. A single 6 V pulse with a width of  

 22. The disadvantage of constant voltage    P = [(V)^2] * R
transmission is    Given = t = 3 min; But, t in hours =
(3/60) hrs.
a)      short circuit current of the system
is increased    Energy = E = P * t
                = ((V)^2 /R) *t
                = ((15)^2 /15 )*(3/60) (for 3
b)      load power factor in heavy loads 24. The depletion mode MOSFET can mins)
operate                 = (225/15) * (1/20)
c)       large conductor area is required for                 = 0.75 kwh 
same power transmission a)      can operate with only positive gate
voltages  26.  A 120-V rms voltage at 60.0 Hz is
d)      all of the above applied across an inductor, a capacitor, and
b)      can operate with only negative gate a resistor in series. If the RMS value of the
  voltages current in this circuit is 0.6 A, what is the
impedance of this circuit?
23. A 30 ohm resistance, a pure c)       cannot operate in the ohmic region
capacitance having a reactance magnitude     a)      100 Ω
of 80 ohm and a pure inductance having a d)      can operate with positive as well as
reactance magnitude of 40 ohm are in negative gate voltages b)      120 Ω
series. The impedance magnitude of this
series combination is nearly:   c)      140 Ω

a)      150 ohm 25. A 15 V source is connected across a d)     200 Ω

15 ohm resistor. How much energy is
b)      50 ohm used in three minutes?  

c)       14.1 ohm a)      75 Wh 27. The synchronous reactance per phase

of a 3-phase star connected 6,600 V
d)      17.1 ohm b)     0.75 Wh synchronous motor is 10 Ω. For a certain
load the input is 900 kW and the induced
   c)      95 Wh line emf is 8900 V. What is the line
current? Neglect resistance
d)      0.95 Wh
    a)      150.5 A
Explanation:
b)      149.4 A (ii) an in-phase voltage booster would  
control the reactive power flow in the
c)       138.6 A system 31. If more than hundred logic gates are
fabricated into single chip, we get a
(iii) the natural loading limit is the lowest
d)      120.8 A
limit for power transfer a)      LSI chip

(iv) thermal limit is the highest limit for b)      MSI chip

power transfer
c)      VLSI chip
28. A 1−φ, synchronous motor has a
back e.m.f. of 250 V, leading by 150
electrical degrees over the applied AM ELECTRONICS (May,2019)
a)      (i) and (ii) are correct only
voltage of 200 volts. The
synchronous reactance of the armature b)      only (ii) is correct 1) Which level of system implementation
includes the specific function oriented
is 2.5 times its resistance. Find the
c)      (ii) and (iii) are correct
registers, counters & multiplexers?
power factor at which the motor is
operating. (A) Module level
d)     all are correct
a)      0.562 (B) Logical level
 
b)      0.9285 (C ) Physical level
30. In an analog switch the aperture time is
the time it takes for the switch to,
c)       0.8726 (D) All of the above
a)      Fully open after the control switches from
d)      0.9621 hold to sample Ans: A

b)      Fully close after the control switches from 2) In digital ICs, Schottky transistors are
  sample to hold
29. Which of the following are true?  preferred over normal transistors because
of their                              
c)      Fully open after the control switches
(i) the quadrature voltage compensator from sample to hold 
would control active power flow in the (A) Lower Propagation
system d)      Fully close after the control switches from
delay                                                              
hold to sample                                                                        
  
(B) Higher Propagation (A) Provide voltage gain (A) Voltage controlled current source 
delay                                                              
                                 (B) Provide phase inversion (B) Voltage controlled voltage source

(C) Lower Power (C) Provide a high-frequency path to (C) Current controlled current source
dissipation                                                    improve the frequency response
(D) Current controlled voltage source
(D) Higher Power (D) Buffer the voltage amplifiers from the
dissipation                                                      low-resistance load and provide impedance Ans: A 
                                                      matching for maximum power transfer
 
Ans: A Ans: D 
7) If gain is +6db and input power is 1mW
3) The UJT may be used as                             for an amplifier; what is output power?

(A) An amplifier                                          5) Which one is true? (A) 1 mW

(B) A Saw tooth (A) Series resonant circuit has high (B) 0 mW
generator                                                        impedance
                                                                      (C) 4 mW
(B) Parallel resonant circuit has low
(C) A impedance (D) None of these
rectifier                                                          
                                                                       (C) At frequency greater than resonance Ans: C 
                                 frequency, circuit behaves like inductive
circuit Explanation: Gain in dB=10
(D) None of the above log(Po/Pi)       So,  6=10
(D) Frequency at which XL=XC log(Po/1mW)                                   
Ans: B
Ans: C Po= 3.9mW or 4mW approx.
 
    
4) Often a common-collector will be the
last stage before the load; the main 6) JFET is;  8) Which motor is used in vacuum cleaner?
function(s) of this stage is to……..
(A) Series (B) Proximity sensor (D) All of the four parameters mentioned
above would be affected
(B) Shunt  (C) Strain guage
Ans: D
(C) Cumulative Compound (D) RCT
 
(D) Differential Compound   Ans: A
13) In a current-series negative feedback
Ans: A (Universal/ DC Series Motor is    amplifier, the input impedance:
used)
11)  In class–A amplifier, the output (A) Increases
  current flows for       
(B) Decreases       
9) What is the average voltage when a (A) a part of the cycle or the input signal
rectangular wave's base line voltage is 20 (C) Remains unchanged       
V, its peak-to-peak voltage is 50 V, and its (B) The full cycle of the input signal
duty cycle is 20%? (D) constant
(C) Half the cycle of the input signal
(A) 26 V Ans:  A 
(D) 3/4th of the cycle of the input signal
(B) 30 V 14) In a voltage-series negative feedback
Ans: B amplifier, the input impedance:
(C) 40 V
  (A) increases
(D) 45 V
12) In an amplifier with negative feedback; (B) decreases       
Ans: B
(A) Only the gain of the amplifier is (C) remains unchanged       
  affected
(D) constant
10) In which sensor, resistance decrease (B) Only the gain and bandwidth of the
with increase in temperature; amplifier are affected Ans:  A 

(A) RTD (C) Only the input and output impedances  

are effected 
15) In two-stage op-amp, what is the (A) Input impedance increases and output (B) A single RC circuit
purpose of compensation circuitry? impedance decreases
(C) A Cascaded amplifier
(A) To provide high gain (B) Input impedance decreases and output
impedance increases (D) A Summing Amplifier
(B) To lower output resistance & maintain
large signal swing (C) Both increases Ans:  B

(C) To establish proper operating point for (D) Both remain the same  Explanation: Laplace of C is 1/s means
each transistor in its quiescent state pole at origin
Ans:  A
(D) To achieve stable closed-loop  
performance  
20) The speed of a DC motor is
Ans: D 18) In a circuit Vdc=200V, the effective
Ac voltage will be; (A) Directly proportional to flux per pole
 
(A) 200 (B) Inversely proportional to flux per pole
16) Which of the following is an
undesirable dynamic characteristic of an (B) 100 (C) Inversely proportional to applied
instrument? voltage
(C) 50
(A) Reproducibility (D) None of the above
(D) 20
(B) Dead zone Ans:  B      (N=Eb/Φ ∝ V−IaRa/Φ )
Ans: A (Effective or RMS value is the
(C) Time lag same as DC value)  

(D) Static error   21) For proper working of transistors in

normal circuit
Ans:  C 19) In terms of circuit components, what
does the term pole refer to? (A) emitter-base junction is reverse biased
   and collector-base junction is forward
(A) A single RL circuit biased
17) In an amplifier with negative feedback;
(B) emitter-base junction is forward biased 23) If R=20 ohm, XL=40 ohm and XC=15  
and collector-base junction is reverse ohm are connected in series and current is
biased 1A, what will be the supply voltage? 25) For a triangular and Sawtooth
waveform the RMS voltage or current
(C) emitter-base junction is forward biased (A) 220V  equals
and collector-base junction is forward
biased  (B) 32V (A)  0.707times peak value

(D) None of them (C) 100V (B)  0.577 times peak value

Ans: B (D) 40V (C)  0.577times average value

   Ans: B    (D)  0.707times Rms value

22) To prevent a DC return between source Explanation: Vs=I x sqrt {(R^2 +(XL- Ans : B
and load, it is necessary to use XC)^2)}
……………… Explanation:   ≈ 0.577 Vpk
 
(A) resistor between source and load  
24) Load impedance ZL=200 ohm,
(B) inductor between source and load Zi=50ohm then characteristic impedance 26) A figure was given having a diode and
Zo= a parallel resistor;
(C) capacitor between source and load
(A) 10000 ohm Ans:  Resistor is used to limit current and
(D) either (A) or (B) diode is used for stopping reverse
(B) 100 ohm breakdown voltage 
Ans: C                                
(C) 200 ohm  
Explanation: Capacitor offers infinite
impedance to DC (D) 4 ohm 27) Which of the item below is an
advantage of a shunt regulator over a series
  Ans: B  type?

Explanation: Zo= Sqrt (ZLxZi)= 100ohm (A) Has an inherent current limiting
(B)  Efficient than series regulator because (C) Capacitor current is linear Ans:  A
of its component used
(D) Capacitor current is constant  
(C)  A non-regulating device
Ans: D 32) For the system in the given figure. The
(D) None of the choices transfer function C(s)/R(s) is
 
Ans: A
30) The output of a signal is given.
  Thermocouple temperature is shown with
voltage, find X?
28)  Using electronic devices as switches,
what is(are) the general methods of T   :     0             5       10
controlling electrical power?
V   :   -6.66       X      -6.82 (A) G1 + G2 + 1
(A) static switching
  (B) G1 G2 + 1
(B) phase control
(A) -2.66 (C) G1 G2 + G2 + 1
(C) zero voltage switching
(B) -6.74   (D) G1 G2 + G1 + 1 
(D) All of the above 
Ans:  A Ans: C 
Ans: D
  Explanation:  Transfer function = (G1 +
  1) G2 + 1 = G1 G2 + G2 + 1
31) Signal Sin (Pi^2n) is periodic with 
29) For a constant input voltage to an  
integrator, why is the voltage across the (A) Period of Pi/2
capacitor linear? 33) Which of the items below is equivalent
(B) Period of pi^2 to a relaxation oscillator?        
(A) Capacitor diode does not dissipate heat
(C) Period of 2pi (A)  Astable multivibrator       
(B) Capacitor current is constantly
changing (D) Aperiodic (B)  Flip-flop       
(C)  Monostable multivibrator        (C) 48 Mbps (D) Sixth

(D) Bistable multivibrator (D) 64 Mbps Ans: D

Ans: A Ans: C  

     37) Which one is correct?

34)  Which of the following statements is Explanation: A noiseless channel can Ans: Transient Response effects the Speed
correct?           carry an arbitrary large amount of While Steady-State Response makes
information, no matter how often it is accuracy
(A) Actuators and transducers are both sampled. If each sample is 3 bits, the
examples of sensors.           channel can send 16 x 106 samples/sec * 3  
bits = 48 Mbps.                
(B) Sensors and transducers are both 38) A circuit was given having transistor
examples of actuators.           The key word here is “noiseless”. With a whose base was grounded, So IB=0A
normal 8KHz channel, Shannon limit hence, Vo=Vce=5v 
(C) Sensors and actuators are both would not allow this.
examples of transducers           Options were:
 
(D) None of them  (A) 5V 
36) Theoretically electromagnetic radiation
Ans: C  field strength varies in inverse proportion (B) 3.1V
to the square of the distance, but when
  atmospheric attenuation effects and the (C) 2.5V
absorption of the terrain are taken into
35) Assuming that the channel is noiseless, account the attenuation can be as high as (D) 0V 
if TV channels are 8 kHz wide with the the inverse _______ power of the distance.
bits/sample = 3Hz and signaling rate = 16  
x 106 samples/second, then what would be (A) Third
the value of data rate?    AM Electrical 
(B) Fourth
(A) 16 Mbps
(C) Fifth
(B) 24 Mbps
40 mcq 2.      A heat sink is generally used with d)      Pin and shackle type
a transistor to ___________
Time: 50 minutes
Negative marking a)      increase the forward current
Calculator was allowed 5.      The hysteresis cycle for the
b)      decrease the forward current material of a transformer core is

c)      compensate for excessive a)      short and wide

Targeted topics : doping
Basic electrical b)     tall and narrow
d)     prevent excessive
AC fundamentals temperature rise c)      tall and wide
Motors
Transformer d)     short and narrow
Power system
Digital electronics 3.      Megger is used to measure

Amplifiers a)      Breakdown voltage of 6.      At high frequency

Oscillator insulation Transformer core is
Controls
b)      Earth resistance a)      Ferrite
 
c)      Insulation resistance b)      soft iron
 
d)     None of the above c)      silicon iron
1.      An RC differentiator acts as a

a)      Low-pass filter
4.      Which type of insulator is used on 7.      An RC series circuit is connected
b)     High-pass filter 132 kV transmission lines? to 300 volt DC source. The voltage
across the capacitor after one time
c)      Band-pass filter a)      Pin type constant is 189.6

d)     Band-stop filter b)       Disc type  

c)       Shackle type
 8.      Digital signals transmitted on a d)      Connect integrator at the a)      Below normal rated speed
single conductor (and a ground) output
must be transmitted in: b)      Above normal rated speed

a)      slow speed c)      Both (a) and (b)

11.  A silicon semiconductor diode
b)      parallel when subjected to ohmmeter d)     None of these
testing gives low resistance in both
c)      serial the directions. Which of the  
following is the correct inference to
be drawn?
d)     analog 13.  A relay is ……….. switch
a)      Diode is faulty
a)      A mechanical
b)       Power failure to the
9.      2's complement of binary number b)      An electronic
Ohmmeter
0101 is 1011.

c)       Diode is short-circuited c)      An electromechanical

        Explanation:  1's complement of
0101 is 1010 and 2's complement is
d)      Diode is open circuited d)     None of the above
1010+1 = 1011

   

Explanation: A proper diode gives a low 14.  An integrating circuit is a simple

10.  How a triangular wave generator is
resistance reading along one direction and RC series circuit with output taken
derived from square wave
high resistance reading along the other. across ………
generator?
Hence, if diode gives low resistance
readings in both the directions, then the a)      Both R and C
a)       Connect oscillator at the
diode must be short-circuited. It’s
output
noteworthy that a faulty diode gives a high b)      R
resistance reading along both the paths.
b)      Connect Voltage follower at
the output c)      C
 
c)       Connect differential at the d)     None of the above
12.  In the flux control method for
output
controlling the speed of D.C. shunt  
motor, the speed control is not
possible
15.  The inputs of a NAND gate are b)      equal to the negative supply 20.  Number of magnetic circuits in a
connected together. The resulting voltage four pole DC machine is
circuit is ………….
c)      equal to zero a)      One
a)      OR gate
d)     equal to CMRR b)      Two
b)      AND gate
  c)      Four
c)      NOT gate
18.  ………….. multivibrator is a square d)     eight
d)     None of the above wave oscillator.

  a)      Monostable
21.  If a copper wire is stretched to
16.  An SCR can exercise control over b)      Astable make it 0.1% longer. What is the
………. of a.c. supply percentage change in its
c)      Bistable resistance?
a)      Positive half-cycles only
d)     none of the above a)      0.2
b)      Negative half-cycles only
  b)      0.4
c)      Both positive and negative
half-cycles 19.  The deflection sensitivity of a CRT c)      1
depends inversely on the
d)     Positive or negative half- d)     2
cycles a)      distance between screen and
defecting plates  
 
b)      length of the vertical deflecting 22.  A resistance R1 is connected with
17.  With zero volts on both inputs, an plates a DC generator and dissipates
OP-amp ideally should have an power if R2 is inserted in Series
output ……….. c)      separation between Y- with it, power dissipated across R1
plates
a)      equal to the positive supply a)      Remain same
voltage d)     defecting voltage
b)      Increases
 
 c)      decreases c)      VSB b) Connecting capacitors in series
with the line
  d)     AM c) Reducing the excitation of the
machines
d) Both a and b
23.  Power factor of induction motor is Explanation: For narrow and wide bands
lagging during frequency modulation, modulation index is
respectively smaller and greater than 1.  
a)      Starting When bandwidth is considered it can be
approximated to AM 29.  Which component of Hartley
oscillator is used in feedback
b)      Operation
  system?
c)      Operation and starting
26.  A current flows in a conductor from a)      Inductor
east to west. The direction of the
 
magnetic field at a point above the b)      Resistor
conductor is: towards north
24.  In open loop control system
c)      Capacitor
 
a)         Output is independent of
d)     Transistor
control input
27.  Power factor of a transformer
Explanation: The feedback used
b)         input is independent of
a)       Leading in Hartley oscillator is Voltage
system parameters
series feedback. Center tapped
b)      Lagging inductors are used in Hartley
c)         system parameters have oscillator to ensure feedback.
effect on the control output These are often in parallel to a
c)      Depends on load
variable capacitor, and feedback is
d)        all of the above sent into the base of the transistor.
d)     None
   
 
25.  When bandwidth is the major 30.  The voltage regulation of an
consideration a narrow and wide 28.  The steady state stability of the alternator with a power factor of
band FM can be approximated to? power system can be improved by: 0.8 lagging is _____ at unity power
factor
a)      DSB-SC a) Increasing the number of
parallel lines between the a)      greater than
transmission points
b)       SSB
 b)      the same as 33.  Spring constant in force-voltage d)     Differentially compounded
analogy is analogous to (negative speed regulation)
c)      smaller than
a)      capacitance  
d)     100%
b)     reciprocal of capacitance 36.  Output of SCR in Cutoff Region
 
c)      current a)      0
31.  An over-excited synchronous
motor running in parallel with d)     resistance b)      Vcc, Ic=0A
induction motors can be used in
improve the power factor of   c)      Vcc/2

a)      supply line 34.  In a control system, usually a d)     Vcc/3

differentiator is not a part it
b)      Transformer because

c)      Generators a)      It reduces gain margin 37.  Energy 500 joule, V = 100v. Q

across capacitor?
d)     all of the above b)      It increases input noise
 
c)      It reduces damping
38.  If a total of 33 MHz of bandwidth is
32.  The position and velocity errors of d)     It increases error allocated to a particular FDD
a type-2 system are cellular telephone system which
  uses two 25 kHz simplex channels
a)      constant, constant to provide full duplex voice and
control channels, compute the
35.  Which motor has the best speed
number of channels available per
b)      constant, infinity regulation?
cell if a system uses 4-cell reuse
c)      zero, constant a)       Series (poor speed
 
regulation)
d)     zero, zero Total bandwidth 33 MHz Channel
b)      Shunt BW=25 kHz: 2 simplex
channels=50 kHz/duplex channel
 
Total available channels =
c)      Commutatively
33,000/50 = 660 channels
compounded
 a)      total number of channels
available per cell 660/ 4 : 165
channels.
b)       95 channels
 

39.  Which of the following can be the

output of PLC?

1. Relay coils
2. Solenoids
3. Indicators
4. Motors
5. Lamps
6. Alarms

a)      Only (1), (2), (3) and (4)

b)     Only (3), (4), (5) and (6)
c)      Only (1), (2), (3) and (5)
d)     All the (1), (2), (3), (4), (5),
and (6)