JEE Main & Advanced Physics Semiconducting Devices Question Bank

done Junction Transistor Total Questions - 44

• question_answer1)
  When NPN transistor is used as an amplifier [AIEEE 2004]
  A)
             Electrons move from base to collector done clear
  B)
             Holes move from emitter to base done clear
  C)
             Electrons move from collector to base done clear
  D)
             Holes move from base to emitter done clear
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• question_answer2)
  The phase difference between input and output voltages of a CE circuit is                                             [MP PET 2004]
  A)
             0o    done clear
  B)
             90o done clear
  C)
             180o                                          done clear
  D)
             270o done clear
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• question_answer3)
  An oscillator is nothing but an amplifier with  [MP PET 2004]
  A)
             Positive feed back              done clear
  B)
             Large gain done clear
  C)
             No feedback                         done clear
  D)
             Negative feedback done clear
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• question_answer4)
  The emitter-base junction of a transistor is ?? biased while the collector-base junction is ??. biased  [KCET 2004]
  A)
             Reverse, forward                done clear
  B)
             Reverse, reverse done clear
  C)
             Forward, forward               done clear
  D)
             Forward, reverse done clear
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• question_answer5)
  In an NPN transistor the collector current is 24 mA. If 80% of electrons reach collector its base current in mA is [Kerala PMT 2004]
  A)
             36   done clear
  B)
             26   done clear
  C)
             16   done clear
  D)
             6 done clear
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• question_answer6)
  A NPN transistor conducts when                            [CPMT 2003]
  A)
             Both collector and emitter are positive with respect to the base done clear
  B)
             Collector is positive and emitter is negative with respect to the base done clear
  C)
             Collector is positive and emitter is at same potential as the base done clear
  D)
             Both collector and emitter are negative with respect to the base done clear
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• question_answer7)
  In the case of constants a and b of  a transistor  [CET 2003]
  A)
             a = b                                        done clear
  B)
             b < 1   a > 1 done clear
  C)
             ab = 1                                      done clear
  D)
             b > 1  a < 1 done clear
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• question_answer8)
  Which of the following is true           [DPMT 2002]
  A)
                     Common base transistor is commonly used because current gain is maximum done clear
  B)
             Common emitter is commonly used because current gain is maximum done clear
  C)
             Common collector is commonly used because current gain is maximum done clear
  D)
             Common emitter is the least used transistor done clear
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• question_answer9)
  If a = 0.98 and current through emitter ie = 20 mA, the value of b is                                          [DPMT 2002]
  A)
             4.9  done clear
  B)
             49 done clear
  C)
             96   done clear
  D)
             9.6 done clear
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• question_answer10)
  For a common base configuration of PNP transistor \[\frac{{{l}_{C}}}{{{l}_{E}}}=0.98\] then maximum current gain in common emitter configuration will be                                                    [CBSE PMT 2002]
  A)
             12   done clear
  B)
             24 done clear
  C)
             6     done clear
  D)
             5 done clear
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• question_answer11)
  In a PNP transistor working as a common-base amplifier, current gain is 0.96 and emitter current is 7.2 mA. The base current is        [AFMC 2002; Pb. PET 2002]
  A)
             0.4 mA                                     done clear
  B)
             0.2 mA done clear
  C)
             0.29 mA                                   done clear
  D)
             0.35 mA done clear
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• question_answer12)
  If \[{{l}_{1}},\,{{l}_{2}},\,{{l}_{3}}\] are the lengths of the emitter, base and collector of a transistor then                                          [KCET 2002]
  A)
             \[{{l}_{1}}={{l}_{2}}={{l}_{3}}\]                                          done clear
  B)
             \[{{l}_{3}}<{{l}_{2}}>{{l}_{1}}\] done clear
  C)
             \[{{l}_{3}}<{{l}_{1}}<{{l}_{2}}\]                                          done clear
  D)
             \[{{l}_{3}}>{{l}_{1}}>{{l}_{2}}\] done clear
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• question_answer13)
  In an NPN transistor circuit, the collector current is 10 mA. If 90% of the electrons emitted reach the collector, the emitter current (iE) and base current (iB) are given by     [KCET 2001]
  A)
             iE = ? 1 mA, iB = 9 mA          done clear
  B)
             iE = 9 mA, iB = ? 1 mA          done clear
  C)
             iE = 1 mA, iB = 11 mA           done clear
  D)
             iE = 11 mA, iB = 1 mA done clear
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• question_answer14)
  In a common emitter transistor, the current gain is 80. What is the change in collector current, when the change in base current is 250 mA                                                     [CBSE PMT 2000]
  A)
             80 ´ 250 mA                            done clear
  B)
             (250 ? 80) mA done clear
  C)
             (250 + 80) mA                        done clear
  D)
             250/80 mA done clear
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• question_answer15)
  Least doped region in a transistor                            [KCET 2000]
  A)
             Either emitter or collector done clear
  B)
             Base done clear
  C)
             Emitter                                    done clear
  D)
             Collector done clear
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• question_answer16)
  The transistors provide good power amplification when they are used in                                              [AMU 1999]
  A)
             Common collector configuration done clear
  B)
             Common emitter configuration done clear
  C)
             Common base configuration                                             done clear
  D)
             None of these done clear
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• question_answer17)
  The transfer ratio of a transistor is 50. The input resistance of the transistor when used in the common-emitter configuration is 1 KW. The peak value for an A.C input voltage of 0.01 V peak is                                   [CBSE PMT 1998]
  A)
             100 mA                                     done clear
  B)
             0.01 mA done clear
  C)
             0.25 mA                                   done clear
  D)
             500 mA done clear
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• question_answer18)
  For a transistor the parameter b = 99. The value of the parameter a is                                    [Pb CET 1998]
  A)
             0.9  done clear
  B)
             0.99 done clear
  C)
             1     done clear
  D)
             9 done clear
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• question_answer19)
  A transistor is used in common emitter mode as an amplifier. Then                                          [IIT-JEE 1998]
  A)
             The base-emitter junction is forward biased done clear
  B)
             The base-emitter junction is reverse biased done clear
  C)
             The input signal is connected in series with the voltage applied to the base-emitter junction done clear
  D)
             The input signal is connected in series with the voltage applied to bias the base collector junction done clear
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• question_answer20)
  In a PNP transistor the base is the N-region. Its width relative to the P-region is                                                 [DCE 1997]
  A)
             Smaller                                    done clear
  B)
             Larger done clear
  C)
             Same                                        done clear
  D)
             Not related done clear
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• question_answer21)
  A common emitter amplifier is designed with NPN transistor (a = 0.99). The input impedance is 1 KW and load is 10 KW. The voltage gain will be                                                       [CPMT 1996]
  A)
             9.9  done clear
  B)
             99 done clear
  C)
             990 done clear
  D)
             9900 done clear
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• question_answer22)
  The symbol given in figure represents            [AMU 1995, 96]
  A)
             NPN transistor done clear
  B)
             PNP transistor done clear
  C)
             Forward biased PN junction diode done clear
  D)
             Reverse biased NP junction diode done clear
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• question_answer23)
  The most commonly used material for making transistor is [MNR 1995]
  A)
             Copper                                    done clear
  B)
             Silicon done clear
  C)
             Ebonite                                   done clear
  D)
             Silver done clear
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• question_answer24)
  An NPN-transistor circuit is arranged as shown in figure. It is [BHU 1994]
  A)
             A common base amplifier circuit done clear
  B)
             A common emitter amplifier circuit done clear
  C)
             A common collector amplifier circuit done clear
  D)
             Neither of the above done clear
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• question_answer25)
  The part of a transistor which is heavily doped to produce a large number of majority carriers, is  [CBSE PMT 1993]
  A)
             Base                                         done clear
  B)
             Emitter done clear
  C)
             Collector                                 done clear
  D)
             None of these done clear
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• question_answer26)
  For a transistor, the current amplification factor is 0.8. The transistor is connected in common emitter configuration. The change in the collector current when the base current changes by 6 mA is [Haryana CET 1991]
  A)
             6 mA                                         done clear
  B)
             4.8 mA done clear
  C)
             24 mA                                      done clear
  D)
             8 mA done clear
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• question_answer27)
  In a common base amplifier circuit, calculate the change in base current if that in the emitter current is 2 mA and a = 0.98  [BHU 1995]
  A)
             0.04 mA                                   done clear
  B)
             1.96 mA done clear
  C)
             0.98 mA                                   done clear
  D)
             2 mA done clear
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• question_answer28)
  In case of NPN-transistors the collector current is always less than the emitter current because [AIIMS 1983]
  A)
             Collector side is reverse biased and emitter side is forward biased done clear
  B)
             After electrons are lost in the base and only remaining ones reach the collector done clear
  C)
             Collector side is forward biased and emitter side is reverse biased done clear
  D)
             Collector being reverse biased attracts less electrons done clear
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• question_answer29)
  In a transistor circuit shown here the base current is 35 mA. The value of the resistor Rb is
  A)
             123.5 kW done clear
  B)
             257 kW done clear
  C)
             380.05 kW done clear
  D)
             None of these done clear
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• question_answer30)
  In a transistor, a change of 8.0 mA in the emitter current produces a change of 7.8 mA in the collector current. What change in the base current is necessary to produce the same change in the collector current
  A)
             50 mA                                       done clear
  B)
             100 mA done clear
  C)
             150 mA                                     done clear
  D)
             200 mA done clear
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• question_answer31)
  In a transistor configuration b-parameter is  [Orissa PMT 2004]          
  A)
             \[\frac{{{l}_{b}}}{{{l}_{c}}}\]   done clear
  B)
             \[\frac{{{l}_{c}}}{{{l}_{b}}}\] done clear
  C)
             \[\frac{{{l}_{c}}}{{{l}_{a}}}\]   done clear
  D)
             \[\frac{{{l}_{a}}}{{{l}_{c}}}\] done clear
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• question_answer32)
  Which of these is unipolar transistor                  [Pb PMT 2004]
  A)
             Point contact transistor    done clear
  B)
             Field effect transistor done clear
  C)
             PNP transistor                      done clear
  D)
             None of these done clear
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• question_answer33)
  For a transistor, in a common emitter arrangement, the alternating current gain b is given by      [DPMT 2004]
  A)
             \[\beta ={{\left( \frac{\Delta {{I}_{C}}}{\Delta {{I}_{B}}} \right)}_{{{V}_{C}}}}\]         done clear
  B)
             \[\beta ={{\left( \frac{\Delta {{I}_{B}}}{\Delta {{I}_{C}}} \right)}_{{{V}_{C}}}}\] done clear
  C)
             \[\beta ={{\left( \frac{\Delta {{I}_{C}}}{\Delta {{I}_{E}}} \right)}_{{{V}_{C}}}}\]         done clear
  D)
             \[\beta ={{\left( \frac{\Delta {{I}_{E}}}{\Delta {{I}_{C}}} \right)}_{{{V}_{C}}}}\] done clear
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• question_answer34)
  The relation between a and b parameters of current gains for a transistors is given by                   [Pb. PET 2000]
  A)
             \[\alpha =\frac{\beta }{1-\beta }\]                                  done clear
  B)
             \[\alpha =\frac{\beta }{1+\beta }\] done clear
  C)
             \[\alpha =\frac{1-\beta }{\beta }\]                                  done clear
  D)
             \[\alpha =\frac{1+\beta }{\beta }\] done clear
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• question_answer35)
  When NPN transistor is used as an amplifier        [DCE 2002]             
  A)
             Electrons move from base to emitter done clear
  B)
             Electrons move from emitter to base done clear
  C)
             Electrons moves from base to emitter done clear
  D)
             Holes moves from base to emitter done clear
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• question_answer36)
  In the CB mode of a transistor, when the collector voltage is changed by 0.5 volt. The collector current changes by 0.05 mA. The output resistance will be            [Pb. PMT 2003]
  A)
             10 kW                                       done clear
  B)
             20 kW done clear
  C)
             5 kW                                         done clear
  D)
             2.5 kW done clear
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• question_answer37)
  Which of the following is used to produce radio waves of constant amplitude                                     [DCE 2004]
  A)
             Oscillator                                done clear
  B)
             FET done clear
  C)
             Rectifier                                  done clear
  D)
             Amplifier done clear
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• question_answer38)
  While a collector to emitter voltage is constant in a transistor, the collector current changes by 8.2 mA when the emitter current changes by 8.3 mA. The value of forward current ratio hfe is                                         [KCET 2002]
  A)
             82   done clear
  B)
             83 done clear
  C)
             8.2  done clear
  D)
             8.3 done clear
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• question_answer39)
  Consider an NPN transistor amplifier in common-emitter configuration. The current gain of the transistor is 100. If the collector current changes by 1 mA, what will be the change in emitter current                                    [AIIMS 2005]
  A)
             1.1 mA                                     done clear
  B)
             1.01 mA done clear
  C)
             0.01 mA                                   done clear
  D)
             10 mA done clear
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• question_answer40)
  In a common base amplifier the phase difference between the input signal voltage and the output voltage is [CBSE PMT 1990; AIEEE 2005]
  A)
             0     done clear
  B)
             \[\pi /4\] done clear
  C)
             \[\pi /2\]                                 done clear
  D)
             \[\pi \] done clear
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• question_answer41)
  In NPN transistor the collector current is 10 mA. If 90% of electrons emitted reach the collector, then [Kerala PMT 2005]
  A)
             Emitter current will be 9 mA done clear
  B)
             Emitter current will be 11.1 mA done clear
  C)
             Base current will be 0.1 mA done clear
  D)
             Base current will be 0.01 mA done clear
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• question_answer42)
  NPN transistor are preferred to PNP transistor because they have           [J & K CET 2005]
  A)
             Low cost done clear
  B)
             Low dissipation energy done clear
  C)
             Capability of handing large power done clear
  D)
             Electrons having high mobility than holes done clear
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• question_answer43)
  In a transistor in CE configuration, the ratio of power gain to voltage gain is          [J & K CET 2005]
  A)
             a    done clear
  B)
             b / a done clear
  C)
             ba done clear
  D)
             b done clear
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• question_answer44)
  In the study of transistor as an amplifier, if \[\alpha ={{I}_{c}}/{{I}_{e}}\] and \[\beta ={{I}_{c}}/{{I}_{b}},\] where \[{{I}_{c}},{{I}_{b}}\] and Ie are the collector, base and emitter currents, then  [CBSE PMT 2000; KCET 2000; Orissa JEE 2005]
  A)
             \[\beta =\frac{1-\alpha }{\alpha }\]                                done clear
  B)
             \[\beta =\frac{\alpha }{1-\alpha }\] done clear
  C)
             \[\beta =\frac{\alpha }{1+\alpha }\]                               done clear
  D)
             \[\beta =\frac{1+\alpha }{\alpha }\] done clear
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