12th Class Physics MCQs Preparation 2022 and Onwards (Unit: Electronics : Set-2 (27 MCQs)) for National MDCAT, ECAT, FPSC, PPSC, JOB Exam, Physics Lecturer, SSC, HSSC (F.Sc.), BS, MS Exams NTS, ETS, etc..



1. In N-type silicon, which of the following statement is true




... Answer is C. Holes are minority carriers and pentavalent atoms are the dopants.
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2. The barrier potential of silicon diode at room temperature is.




... Answer is B. 0.7 V
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3. The width of the depletion region of a junction




... Answer is C. Increases under reverse bias
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4. For common emitter configuration of NPN transistor current gain is given by




... Answer is A. `\I_C`/`\I_B`
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5.  The reverse saturation current in a PN junction diode is only due to




... Answer is B. minority carriers
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6. PN junction when reversed biased act as:




... Answer is D. OFF Switch
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7. Improper biasing of a transistor circuit produces :




... Answer is B. Distortion in the output signal
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8. When transistors are used in digital circuits they usually operate in the:




... Answer is C. Saturation and cutoff regions
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9. Most of the electrons in the base of an NPN transistor flow:




... Answer is B. into the collector
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10. In a transistor, the collector current is controlled by:




... Answer is B. base current
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11. The minimum number of diode required for full wave rectification are




... Answer is C. 2
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12. In a transistor both collector-base and base-emitter junctions are reverse-biased then it is




... Answer is B. Cutoff region
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13. What does ICs stand for in electronics




    ... Answer is C. Integrated circuits
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    14.  Which of the following is NOT a semiconductor device:




    ... Answer is D. Capacitor
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    15. A pure semiconductor without any significant impurity or dopant species added is called




    ... Answer is A. Intrinsic semiconductor
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    16.. The resistivity of semiconductor materials with respect to conductors or insulators are:




    ... Answer is C. Lies between Insulators and conductors
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    17. Germanium Ge and silicon Si are _________solid according to their structure::




    ... Answer is A. Crystalline
      -
    Germanium Ge and silicon Si crystalline structure and these materials are tetravalent, i.e. each atom has four valance electrons in the outer shell. Each atom shares it four valance electrons with each of its hour neighboring atoms as shown in the figure. 


    18. At some temperature T (let a room temperature) some covalent bonds break down the electron become free and leaving vacancies in the valance band called holes. These holes act as




    ... Answer is B. Positive Changes
      -
    -


    19. The electrical conductivity of intrinsic semiconductors at room temperature is




    ... Answer is B. Small
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    20. The conductivity of semiconductor can be improved by adding an impurity of which of the following atoms into a pure semiconductor.




    ... Answer is C. Either (A) or (B)
    The conductivity of semiconductors can be improved by adding impurities of either pentavalent or trivalent atoms into a pure semiconductor.


    21. When an impurity of pentavalent (valency 5) element like arsenic (As), antimony (Sb), Phosphorus (P), etc. is added to a pure semiconductor (germanium, silicon) in a specific ratio then such a doped semiconductor is called




    ... Answer is B. N-type semiconductor
      -
    -


    22. When an impurity of trivalent (valency 3) element like boron (B), gallium (Ga), Indium (In), etc. is added to a pure semiconductor (germanium, silicon) in specific ratio then such doped semiconductor is called




    ... Answer is A. P-type semiconductor
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    23. In N-type semiconductors, the doping of Germanium is taken place with




    ... Answer is B. Pentavalent
    When an impurity of pentavalent (valency 5) element like arsenic (As), antimony (Sb), Phosphorus (P), etc. is added to a pure semiconductor (germanium, silicon) in a specific ratio then such a doped semiconductor is called an N-type semiconductor


    24. The majority of charge carriers in N-type semiconductors are




    ... Answer is A. Free electrons
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    25.  The majority of charge carriers in P-type semiconductors are




    ... Answer is B. Holes
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26. The potential difference across the germanium PN junction is




... Answer is C. 0.3 V
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27. When the P-type of the PN-Junction is connected with the Positive terminal and the N-type with the negative terminal of the battery, then such a biasing is known as:




... Answer is B. Forward-biased PN Junction
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