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Sunday, July 31, 2011

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ELECTRONIC DEVICES


ELECTRONIC DEVICES
1. FET
a.has a very high input impedance
b.depends on minority carrier flow
c.uses a forward biased junction
d.uses a high concenteration emitter junction
2. A PNPN device having no gate is called
a.UJT
b.Triac
c.Schockley diode
d.SCR
3. When a pure semiconductor is heated
a.its resistance increases
b.its resistance decreases
c.its atomic structure changes
d.it becomes metal
4. Pure semiconductors are poor conductor because
a.they have no valence electrons
b.all valence electrons are in electron pairs
c.they have a number of holes
d.there are fewer electrons than protons
5. An intrinsic semiconductor at absolute zero temperature
a.has only a few holes and a few electrons
b.has very large number of holes and electrons
c.behaves like a good conductor
d.behaves like a good insulator
6. Injected minority carriers are the minority carriers which
a.are in excess of the number of majority carriers
b.are impurely generated
c.are thermally generated
d.are in excess of the equilibrium number
7. The diffusion length of a carrier depends on
a.the shape to the semiconductor
b.the lifetime of the carriers alone
c.mobility and lifetime of the carriers
d.the mobility of the carriers alone
8. In gunn diode, negative resistance result from
a.avalanche breakdown due to high voltage gradient
b.electron transfer to an energy level with less mobility
c.tunnelling across the junction
d.electron domains forming at the junction
9. The main advantage of TRAPATT diode over IMPATT diode is its
a.higher output
b.higher efficiency
c.lower noise
d.capability to operate at higher frequencies
10. Transferred electron mechanism involved in Gunn diode consists in transfer of electrons
a.from valence band to conduction band
b.from valence band to satellite valley
c.from central valley to satellite valley
d.from satellite valley to central valley
11. Performance of the following diode is not bases on its negative resistance characteristic
a. Gunn diode
b.IMPATT diode
c.Tunnel diode
d.LSA diode
12. LCD consumes power of the order of
a.a few microwatts
b.a few milliwatts
c.hundreds of milliwatts
d.a few watts
13. In schottky barrier diode, conduction is
a.entirely by electrons
b.entirely by holes
c.mainly by holes but  partly by electrons
d.mainly by electrons but partly by holes
14. Unijunction transistor
a.has only one pn junction
b.has two pn junction
c.is a unipolar device
d.is a bulk semiconductor device
15. The temperature coefficient of breakdown diode is defined as _________
a.rate of change of breakdown voltage with temperature
b.rate of change of dynamic resistance with temperature
c.rate of change of power handling capacity with temperature
d.rage of change of diode current  with temperature
16. Zener breakdown diodes have breakdown voltage which
a.has positive temperature coefficient
b.has negative temperature coefficient
c.is independent of temperature
d.none of these
17. On increasing the current through the zener diode by a factor of 2, the voltage across the diode
a.gets doubled
b.becomes half
c.remains almost unchanged
d.becomes 4 times as large
18. The dynamic resistance of a zener diode
a.increases with increase of its current
b.decreases with increase of its current
c.is almost independent of current
d.may increase or decrease with increase of current
19. Avalanche breakdown results at applied
a.forward bias exceeding about 6 volt
b.forward bias below 6 volts
c.reverse bias exceeding about 6 volt
d.reverse bias below 6 volt
20. Tunnel diode is a pn diode with
a.very high doping in p region
b.very high doping in n region
c.very high doping in both   p and n region
d.low doping in both p and n region
21. The most important application of tunnel diode is
a.as rectifier
b.as switching device in digital circuits
c.as voltage controllable device
d.as oscillator
22. Avalanche breakdown results basically due to ________
a.impact ionization
b.strong electric field across the junction
c.emission of electrons
d.rise in temperature
23. LEDs fabricated from GaAs emit radiation in the _____
a.ultraviole region
b.infrared region
c.visible region
d.none of these
24. In LED, when excited electrons revert from conduction band to valence band, the phenomenon utitlized is
a.radioactive recombination
b.formation of photons
c.energy transfer from one electron band to another
d.none of these
25. A semiconductor photodiode uses _____
a.photoemissive effect
b.photovoltaic effect
c.photoconductive effect
d.none of these
26. Response time of PIN photodiode is of the order of ___________
a.0.1 ns
b.1 ns
c.10 ns
d.1 ms
27. In phototransistor, light is focussed to fall on ______
a.emitter to base junction
b.collector to base junction
c.base region only
d. all the three regions of the transistor
28. Diac is a
a.2 terminal bidirectional switch
b.2 terminal unilateral switch
c.3 terminal bidirectional switch
d.3 terminal unilateral switch
29. Diac is a silicon device with
a.3 layers and one gate
b.3 layers and no gate
c.4 layers and one gate
d.4 layers and no gate
30. Thermistor is used for measurement of power at
a.audio frequencies
b.high frequencies
c.very high frequencies
d.microwate frequencies
31. Traic is a _____
a.2 terminal bidirectional switch
b.3 terminal bidirectional switch
c.2 terminal unilateral switch
d.3 terminal unilateral switch
32. In a SCR, the breakover voltage VBO ______
a.independent of gate current
b.increases with increase of positive gate current
c.decreases with increase of positive gate current
d.may increase or decrease with increase of gate current depending on temperature
33. After firing an SCR,if the gate pulse is removed, the SCR current ___
a.remains the same
b.reduces to zero
c.rises up
d.rises a little and then falls to zero
34. In a transistor amplifier, the reverse saturation current  ______
a.doubles for every 10 deg C rise in temperature
b.doubles  for every 1 deg C rise in temperature
c.increase linearly with temperature
d.doubles for every 5 deg C rise in temperature
35. SCR uses
a.no gate
b.one gate on the p layer next to cathode
c.one gate on the n layer next to anode
d.two gates
36. In a pn diode, the hole diffuse from p region to n region because ______
a.there is higher concentration of holes in the p region
b.holes are positively charged
c.holes are urged to move by the barrier potential
d.the free-electron in the n region  attract the holes
37. In an unbiased pn junction, the junction current at equilibrium is _________
a.due to diffusion of majority carriers
b.due to diffusion of minority carriers
c.zero due to equal and opposite currents crossing the junction
d.zero because no charges cross the junction
38. The intrinsic stand off ratio of UJT lies in the range of _____
a.0.05 to 0.07
b.0.5 to 0.8
c.0.1 to 0.4
d.any other value
39. LED uses _______ when excited electron reverts from conduction band to valence band.
a.radiative combination
b.formation of phonons
c.energy transfer from one electron to another
d.none of  the above
40. FET has offset voltage of about _________
a.0.2V
b.6 V
c.1.1 V
d. zero
41. Say true or false
(i) FET has higher input impedance than BJT
(ii) FET produces more noise than BJT
a.(i) is true,(ii) is false
b(i) is false,(ii) is true
c.(i) and (ii) are true
d.(i) and (ii) are false
42. In a npn transistor in CB configuration only 0.5% of electrons injected into the base recombine with the majority carrier holes in the base. If 108  electrons enter the emitter per µs, how many electrons come out of (i)the base lead and (ii) the collector lead.
a.(i) 5×105 (ii) 995×105
b. .(i) 5×104 (ii) 995×103
c. .(i) 6×105 (ii) 995×107
d. .(i) 995×105 (ii) 5×105 
43. In a reverse biased pn diode , the density of minority carrier holes in the n region at the junctions equals __________
a.thermal equilibrium pno
b.zero
c.pno/2
d.pnn/4
44. The cut-in voltage for Ge diode is approximately
a.0.2V
b.0.6V
c.1.1V
d.any other value
45 . The reverse saturation current in Si diode is of the order of
a.1nA
b.1 µA
c.1 mA
d.100 mA
46. Find the resistivity of intrinsic germanium at 300 deg.K. It is given that ni at 300 deg.K is 2.5×1013/cm3 and µn and µp     are 3800 and 1800 cm2/V-S.If donor impurities are added to the extent of 1 impurity atom per 5×107 germanium atoms find resistivity.
a.32.6 Ω-cm ,1.66 Ω-cm
b.30 Ω-cm,1.54 Ω-cm
c.44.6 Ω-cm,1.86 Ω-cm
d.20 Ω-cm,4.98 Ω-cm
47. In an n-type semiconductor , if the concentration of donor atoms is increased by a factor of 4 find the shift in the position of Fermi level. Assume kT=0.03eV.
a.upward shift of 0.0416 eV
b.downward shift of 0.0416eV
c.upward shift of 0.2314eV
d.downward shift of 0.2314 ev
48. The depletion region in an open circuited pn junction contains
a.electrons
b.holes
c.uncovered immobile impurity ions
d.neutralized impurity atoms
49. The reverse saturation current in pn diode _____________  with increase of reverse bias.
a.increases
b.decreases
c.remains constant
d.increases exponentially
50. The reverse saturation current I0 for a Ge diode varies as
a.T3
b.T2
c.T
d.T1.5
ELECTRONIC CIRCUITS - I
1. The d.c load line of a transistor circuit
            a) is a graph between Ic and Vce                                   b) is a graph between Ic and Ib
            c) does not contain the locating point                   d) is a curved line
2. The positive part of the output signal in a transistor circuit starts clipping, if Q-point of the circuit moves
            a) towards the saturation point                            b) towards the cut-off point
            c) towards the center of the load line                  d) none of the above
3. The voltage divider biasing circuit is used in amplifier quite often because it
            a) limit the a.c signal going to the base
            b) makes the operating point almost independent of β
            c) reduces the d.c base current
            d) reduces the cost of the circuit
4. Which of the following components are used for bias compensation in transistor circuits?
            a) resistors                                                        b) rectifier diodes
            c) thermistors                                                    d) both (b) and (c) above
5. To avoid thermal run away in the design of analog circuit, the operating point of the BJT should be such that it satisfies the condition
            a) Vce=1/2 Vce                                                            b) Vce ≤ ½ Vcc
            c) Vce >1/2 Vcc                                               d) Vce ≤ 0.78 Vcc
6. In the case of BJT amplifier, bias stability is achieved by
            a) Keeping the base current constant
            b) Changing the base current in order to keep the Ic and Vcb constant
            c) Keeping the temperature constant
            d) Keeping the temperature and the base current constant
7. For a transistor amplifier with self-biasing network, the following components are used R1 = 4kΩ, R2 = 4kΩ, and Re =1kΩ the approximate value of the stability factor S will be
            a) 4                              b) 3                              c) 2                              d) 1.5
8. Improper biasing of a transistor circuit leads to
            a) excessive heat production at collector terminal
            b) distortion in output signal
            c) faulty location of load line
            d) heavy loading of collector terminal
9. The negative output swing in a transistor circuit starts clipping first when Q point
            a) has optimum value                                         b) is near saturation point
            c) is near cut-off point                                       d) is in the active region of the load line
10. When a BJT is employed as an amplifier , it operates
            a) in cut-off                                                       b) in saturation
            c) well into saturation                                         d) over the active region
11. Which of the following method used for biasing a BJT in integrated circuits is considered independent of transistor β ?
            a) fixed biasing                                                  b) voltage divider bias
            c) collector feedback bias                                  d) base bias with collector feedback
12. Thermal runaway will take place if the Q point is such that
            a) Vce >1/2 Vcc                                               b) Vce <Vcc
            c) Vce < 2Vcc                                                  d) Vce < ½ Vcc
13. The voltage gain of a common base amplifier is
            a) zero                                                              b) less than unity
            c) unity                                                             d) greater than unity
14. For a common base transistor amplifier having input resistance Ri and output resistance Ro , which of the following statements holds good
            a) Ri is low, Ro is high                                       b) Ri is high, Ro is low
            c) Ri and Ro are both medium                            d) both are same
15. The current gain of an emitter follower is
            a) zero                                                              b) greater than unity
            c) less than unity                                               d) all of them
16. Which of the following transistor amplifies has the highest voltage gain
            a) common base                                                b) common collector
            c) common emitter                                            d) none of them
17. In an ac amplifier , larger the internal resistance of the ac signal source
            a) greater the overall voltage gain                       b) greater the input impedance
            c) smaller the current gain                                  d) smaller the circuit voltage gain
18. The main use of an emitter follower is as
            a) power amplifier                                             b) impedance matching device
            c) low-input impedance circuit                            d) follower of base signal
19. An ideal amplifier is one which
            a) has infinite voltage gain
            b) responds only to signal at its input terminals
            c) has positive feedback
            d) gives uniform frequency response
20. When emitter bypass capacitor in a common-emitter amplifier is removed, its-------------------- is considerably reduced.
            a) input resistance                                             b) output load resistance
            c) emitter current                                              d) voltage gain
21. Unique features of a CC amplifier circuit is that it
            a) steps up the impedance level
            b) does not increases signal voltage
            c) acts as an impedance matching device
            d) all of the above
22. The h-parameters are called hybrid parameters because they
            a) are different from y-and z-parameters
            b) are mixed with other parameters
            c) apply to circuits contained in a box
            d) are defined by using both open circuit and short circuit terminations
23. Which of the following statement is not correct regarding the h-parameters of a transistor
            a) the values of h-parameters can be obtained from transistor characteristics
            b) their values depends upon the transistor configuration
            c) their values depends on operating point
            d) they are four in number
24. Which of the following four h-parameters of a transistor has a greatest value?
            a) hi                  b) hr                 c) ho                 d) hf
25. Which of the following four h-parameters of a transistor has a smallest value?
            a) hi                  b) hr                 c) ho                 d) hf
26. The h-parameters of a transistor depends on its
            a) configuration                                                 b) operating point
            c) temperature                                                  d) all of the above
27.The output admittance ho of an ideal transistor connected is common base configuration is --------------- siemens
            a)0                   b) 1/r                c)1/βre             d)-1
28.A transistor has hfe = 100, hie =5.2k and rbb=  0.
At room temperature , VT=26 mV. The collector current ,Ic will be
            a) 10 mA          b) 5 mA            c) 1 mA            d) 0.5 mA
                                               
29. The gain of the cascaded amplifier is equal to the
            a) product of individual gains                                          b) sum of individual gains
            c) radio of stage gains                                                    d) none of these
30. Two stages of a multistage amplifier have a gains of 50 and 20. The dB voltage gain is
            a) 3                  b) 30                 c) 300               d) 1000
31. The RC coupling is popular in audio amplifiers because
            a) It provides an output signal in phase with the input signal
            b) It needs low voltage collector supply
            c) It has better audio frequency response
            d) none of these
32. The major advantage of a direct coupled amplifier is that
            a) It uses less number of components
            b) It has very good temperature stability
            c) It does not use frequency sensitive components
            d) It can amplify direct current and low frequency signals
33. In a darlington pair,
            a) the two transistors are connected in parallel
            b) the emitter of the first transistor feeds the base of the second
            c) the collector of the first transistor feeds the base of the second
            d) none of these
34. The overall bandwidth of two identical voltage amplifiers connected in cascade will
            a) remain same as that of a single stage
            b) be worse than that of a single stage
            c) be better than that of a single stage
            d) be better if stage gain is low and worse if stage gain is high
35. The darlington pair is mainly used for
            a) impedance matching                                                  b) wide band voltage amplification
            c) power amplification                                                   d) reducing distortion
36. The best location for setting a Q-point on dc load line of an FET amplifier is at
            a) saturation point                                                          b) cut-off point 
            c) mid-point                                                                   d) none of these
37. Which of the following technique is used for biasing the enhancement type MOSFET?
            a) voltage divider bias                                                    b) collector feedback bias
            c) current source bias                                                    d) self bias
38. The maximum collector circuit efficiency of class-A amplifier with a transformer coupled
            a) 25%             b) 50%             c) 78.6%           d) 95.4%
39. Class-A power amplifiers, as compared to class-B amplifiers
            a) have more efficiency
            b) have less distortion
            c) are not susceptible to power supply hum
            d) none of the above
40. High power efficiency of a push-pull amplifier is due to the fact that
            a) each transistor conducts on different cycles of input
            b) transistors are placed in CE configuration
            c) there is no quiescient collector current
            d) low forward biasing voltage is required
41. The maximum overall efficiency of a transformer coupled class-A amplifier is -----------%
            a) 78.5              b) 25                 c) 50                 d) 85
42. A class-B push-pull amplifier has the main advantage of being free from
            a) any circuit imbalances                                    b) unwanted noise
            c) even-order harmonic distortion                       d) d.c magnetic saturation effects
43. Crossover distortion occurs in ---------------- amplifiers.
            a) push-pull                   b) class-A                     c) class-B         d) class-AB
44. The maximum overall efficiency of a class-B push-pull amplifier cannot exceed----------percent.
            a) 100               b) 78.5              c) 50                 d) 85
45. Class AB operation is often used in power amplifiers in order to,
            a) get maximum efficiency                                 b) remove even harmonics
            c) overcome crossover distortion                        d) reduce collector dissipation
46. The ripple factor of a bridge rectifier is
            a) 0.482            b) 0.812            c) 1.11              d) 1.21
47. The use of a capacitor filter in a rectifier circuit gives satisfactory performance only when the load
            a) current is high                                               b) current is low
            c) voltage is high                                               d) voltage is low
48. A half wave rectifier is equivalent to
            a) A clamper circuit                                           b) A clipper circuit
            c) A clamper circuit with negative bias               d) A clamper circuit with positive bias
49. The basic reason why a full-wave rectifier has a twice the efficiency of a half-wave rectifier is that
            a) it makes use of transformer
            b) its ripple factor is much less
            c) it utilizes both half-cycle of the input
            d) its output frequency is double the line frequency
50. If the input supply frequency is 50Hz ,the output ripple frequency of a bridge rectifier is -----------Hz   
            a) 100               b) 75                 c) 50                 d) 25


ELECTRONIC CIRCUITS - II
1.       When input signal and part of output signal are in phase , the feedback is called -------
a.       Negative feedback
b.       Positive feedback
c.       Null feedback
d.       None of the above
2.       Positive feedback is used in -------
a.       Amplifiers
b.       Rectifiers
c.       Oscillators
d.                                                                                           Switches
3.       An ideal current amplifier must have------
a.       Infinite input resistance and zero output resistance
b.       Zero input resistance and Infinite output resistance
c.       Infinite input resistance and Infinite output resistance
d.       Zero input resistance and zero output resistance
4.       An ideal transconductance amplifier must have-----
a.       Infinite input resistance and zero output resistance
b.       Zero input resistance and Infinite output resistance
c.       Infinite input resistance and Infinite output resistance
d.       Zero input resistance and zero output resistance
5.       The value of feedback factor β is------
a.       Zero
b.       One
c.       Lies between zero and one
d.       Lies between -1 and +1
6.       Sensitivity of the transfer gain is-----
a.       1/( 1+βA)
b.       1+βA
c.       A/(1+βA)
d.                                                                                           (1+βA)/A
7.       Signal feedback--------
a.       Reduces the amount of noise signal and non linear distortion
b.       Reduces the amount of noise signal and increases non linear distortion
c.       Increases the amount of noise signal and increases non linear distortion
d.                                                                                           Increases the amount of noise signal and reduces non linear distortion
8.       For the current series feedback amplifier gain with feedback is -----
a.       Avf=Av /(1+β Av)
b.       Rmf=Rm /(1+β Rm)
c.       Aif=Ai /β Ai
d.                                                                                           Gmf=Gm /(1+β Gm)
9.       For the voltage shunt feedback amplifier gain with feedback is -----
a.       Avf=Av /(1+β Av)
b.       Rmf=Rm /(1+β Rm)
c.       Aif=Ai /β Ai
d.       Gmf=Gm /(1+β Gm)
10.   For the voltage shunt feedback amplifier , the sampling signal is -----
a.       voltage
b.       current
c.       both (a) and (b)
d.                                                                                           power
11.   To find input loop and output loop for the current series feedback amplifier, make the respective
a.       Io=0 and Ii=0
b.       Vo=0 and Ii=0
c.       Io=0 and Vi=0
d.       Vo=0 and Vi=0
12.   For the voltage series feedback amplifier, the input resistance with feedback is
a.       Rif = RiD
b.       Rif = RiAv
c.       Rif = Ri /D
d.       Rif = RiAi  
13.   The frequency response of the negative feedback amplifier gets
a.       Improved
b.       Decreased
c.       No change
d.       None of the above
14.   For an oscillator, to start with oscillations, the product Aβ should be
a.       Aβ =1
b.       Aβ >1
c.       Aβ <1
d.       Aβ =0
15.   For a RC phase shift oscillator, the phase angle Φ of the circuit depends on,
a.       R & C values
b.       Inductors
c.       Resistances
d.       Input signal
16.   The frequency of the transistorised RC phase shift oscillator is
a.       F=1/ (2πRC(4k+6)½ )
b.       F=1/ (2πRC(6)½ )
c.       F=1/ (2πRC)
d.       F=1/ (2π(LC)½ )
17.   For the phase shift oscillator using op-amp, the frequency of oscillation is
a.       F=1/ (2πRC(4k+6)½ )
b.       F=1/ (2πRC(6)½ )
c.       F=1/ (2πRC)
d.                                                                                           F=1/ (2π(LC)½ )
18.   The frequency of the Wien bridge oscillator , if the R and C values of the sensitive arms are equal is
a.       F=1/ (2πRC(4k+6)½ )
b.       F=1/ (2πRC(6)½ )
c.       F=1/ (2πRC)
d.       F=1/ (2π(LC)½ )
19.   The frequency of oscillation for the Hartley oscillator is
a.       F=1/ (2πRC(4k+6)½ )
b.       F=1/ (2πRC(6)½ )
c.       F=1/ (2πRC)
d.       F=1/ (2π(LeqC)½ )
20.   The factors affecting the stability of an oscillator are
                     i.      Due to change in temperature
                   ii.      Variation in the power supply
                  iii.      Changes in the load connected
                 iv.      Capacitance effect in transistor and stray capacitances
     Which is true?
a.       (i) & (ii) alone
b.       (i) & (iv) alone
c.       (ii) & (iii) alone
d.       (i),(ii), (iii) & (iv)
21.UJT Relaxation oscillator uses,
e.       Negative resistance device
f.        Positive feedback network
g.       Negative feedback network
h.       None of the above
22.Oscillator circuit
(a)                            Cannot be operated in class-A condition
(b)                            Can be operated in class-A condition to give sinusoidal waveform
(c)                            Can be operated in class-A condition to give distorted waveform
(d)    Can be operated in class-A condition to give better waveshape 

23.Copper loss is
a)      Inversely proportional to frequency
b)      Directly proportional to frequency
c)      Independent to frequency
d)      None of the above
24.Quality factor Q is defined as the ratio of
a.       Resistance to reactance
b.       Reactance to resistance
c.       Reactance to inductance
d.       Reactance to capacitance
25.The bandwidth of the resonant circuit is given as
a.       Bandwidth= fr
b.       Bandwidth= QL /  fr
c.       Bandwidth=  fr / R
d.       Bandwidth= fr / QL    
26.The relation between the effective quality factor Qeff and the fractional change in resonant frequency δ for the tuned amplifier is given as
a.       δ =1/ Qeff
b.       δ =1/ 2Qeff
c.       δ =2Qeff
d.       δ = f / 2Qeff                
27.If the resonant frequencies of the two single tuned cascaded amplifiers are adjusted and separated by an amount equal to the bandwidth of each stage is known as
a.          Single tuned amplifier
b.          Double tuned amplifier
c.       Stagger tuned amplifier
d.       Oscillator              
28.At high frequencies, the inter junction capacitance between base and collector Cbc of the transistor becomes
a.       Independent
b.                Reduced
c.       Dominant
d.       No change    
29.The output signal of the class-C amplifier is ------- for a full input cycle.
a.       Less than a half cycle
b.       Equal to the input signal
c.       Greater than a half cycle
d.       Full cycle      
30.The bandwidth of the class-C tuned amplifier is given as
a.       Ratio between resonant frequency to the Quality factor
b.       Ratio between Quality factor to the resonant frequency
c.       Ratio between resonant frequency to the Resistance
d.       Ratio between Resistance to the resonant frequency
31.When the mixer is used to translate the signal frequency to lower frequency it is termed as
a.       Ripple counter
b.       Up counter
c.       Down counter
d.       Ring counter
32.The circuits used to generate non sinusoidal waveforms are called as
a.       Multivibrators
b.       Oscillators
c.       Generators
d.       Oscilloscopes                           
33.The multivibrator is a
a.       Single stage amplifier
b.       Tuned amplifier
c.       Three stage amplifier
d.       Two stage amplifier  
34.Which of the following is not true.
(a)    An oscillator is a circuit that converts DC to AC
(b)    An oscillator is a amplifier that supplies its own signal
(c)    An oscillator generate sine waves
(d)    In phase feedback is called positive feedback
35.What conditions are required for an amplifier to oscillate
(a)    There must be feedback
(b)    The feedback must be in phase
(c)    The gain must be greater than the loss
(d)    All the above are required
36.A Hartley oscillator circuit uses
a.       Capacitive feedback
b.       A tapped inductor
c.       A tapped capacitor
d.       A tapped inductor for inductive feedback
 37.Bootstrap principle is concerned with
a.       Darlington connection
b.      Multistage amplifier
c.       Current controlled current source
 d.   None of the above
38.The response curve of a double tuned circuits shows two peaks when the transformer has
a.       Loose coupling
b.       Critical coupling
c.       Light coupling
d.       Excessive damping
39.Value of fs of a crystal with L = 1H, C = 0.01pF, R = 1000W, Cin = 20Pf
    1. 1189KHz
    2. 1289KHz
c.    1389KHz
d.       1589KHz
40.In a Hartley oscillator L1 = 15Mh, C = 50pF, calculate L2 for a frequency of 168KHz. The mutual inductance between L1 and L2 is 5mH
a.       5mH
b.       2.9mH
c.       3.1mH
d.       4.4mH
41.The astable multivibrator circuit is shown below. What waveform should be expected at the collector of Q1.
a.       Sawtooth
b.       Pulse
c.       Sinusoidal
d.       Square

42.What is the phase relationship of the signal at the collector of Q2 to the signal at the collector of Q1.
a.       0 degree
b.       90 degree
c.       180 degree
d.       360 degree
43.Refer to fig of a UJT relaxation oscillator, what waveform should appear across capacitor,
a.       Sawtooth
b.       Pulse
c.       Sinusoidal
d.       Square
44.In the oscillator shown , the feedback is
a.       Regenerative
b.       Degenerative
c.       Either of (a) or (b) above
d.       Zero
45.The  Astable multivibrator requires ----- external triggers
a.       One
b.       Two
c.       Three
d.       No
46.In phase shift oscillator for phase shift which of the following can be used
(a)    RC network
(b)    Voltage shunt feedback
(c)    Emitter follower
(d)    Any of the above 
47. Parasitic oscillation are
(a)    Free from distortion
(b)    Unwanted oscillation created due to stray capacitance and inductance
(c)    Mechanical oscillation of the equipment resulting in either increase or reduction of oscillation produced is a oscillator
(d)    Harmonic oscillations
48.The multivibrator can be used as a
(a)    Cavity resonator
(b)    Harmonic generator
(c)    Waveform modifier
(d)    Any of the above
49. Darlington connection of three or more transistors is not practical because
(a)    Leakage current of first transistor is amplified by the second
(b)    Thermal run away may arise
(c)    The input resistance does not increase accordingly
(d)    It is not possible to connect
50.  To nullify the junction capacitance which is dominant at high frequencies is termed as
e)      Nullification
f)       Cancellation
g)      Neutralization
h)      Collapsing