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Semiconductor Electronics Model Question Paper

12th Standard

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Physics

Time : 01:00:00 Hrs
Total Marks : 50
    4 x 1 = 4
  1. If a small amount of antimony (Sb) is added to germanium crystal,______.

    (a)

    it becomes a p-type semiconductor

    (b)

    the antimony becomes an acceptor atom

    (c)

    there will be more free electrons than hole in the semiconductor

    (d)

    its resistance is increased

  2. A forward biased diode is treated as ________________.

    (a)

    An open switch with infinite resistance

    (b)

    A closed switch with a voltage drop of 0V

    (c)

    A closed switch in series with a battery voltage of 0.7V

    (d)

    A closed switch in series with a small resistance and a battery

  3. C, Si and Ge have same no of valence electrons. C is an insulator because energy required to take one electron out from ______________.

    (a)

    Si is more

    (b)

    C is more

    (c)

    Ge is more

    (d)

    C is less

  4. By adding _________ impurity in intrinsic semi conductor, p type semiconductor is made. Charge of these p type semiconductor is ____________

    (a)

    Trivalent, neutral

    (b)

    Pentaralent, neutral

    (c)

    Pentavalent, positive

    (d)

    Trivalent, negative

  5. 1 x 2 = 2
  6. Assertion: Base current (IB) decreases and in turn increases the collector current.
    Reason: Input signal (VS) decreases the forward voltage across the emitter-base.
    Codes:
    (a) Assertion and Reason are correct and Reason is the correct explanation of Assertion.
    (b) Assertion and Reason are true but Reason is the false explanation of the Assertion.
    (c) Assertion is true but Reason is false.
    (d) Assertion is false but Reason is true.

  7. 1 x 2 = 2
  8. (a) ENIAC World's first computer
    (b) Energy levels Electron volts
    (c) Bipolar junction Bardeen
    (d) Reverse saturation current IR
  9. 2 x 1 = 2
  10. Correct Statement
    (I) Transistor can be operated efficiently in an operating point
    (II) Variations of Ic and VCE takes place in this point.
    (III) Q - points determine the working point of a transistor.
    (IV) Transistor is a semiconductor device used to amplify or switch electronic signals.
    (a) I and II only
    (b) II and III only
    (c) I, II and III only
    (d) I, II, III and IV only

  11. Incorrect statements
    (a) A and B are inputs and Y is the output for OR gate.
    (b) A is the input and Y is the output for NOT gate.
    (c) A and B are outputs and Y is the input for NOR gate.
    (d) A and B are inputs and Y is the output for Ex-OR gate.

  12. 3 x 2 = 6
  13. Define electron motion in a semiconductor.

  14. Distinguish between intrinsic and extrinsic semiconductors.

  15. Define energy band

  16. 3 x 3 = 9
  17. Elucidate the formation of a N -type and P-type semiconductors.

  18. Explain the formation of depletion region and barrier potential in PN junction diode.

  19. Draw the circuit diagram of a half-wave rectifier and explain its working.

  20. 3 x 5 = 15
  21. The given circuit has two ideal diodes connected as shown in figure below. Calculate the current flowing through the resistance R1.

  22. The current gain of a common emitter transistor circuit shown in figure is 120. Draw the DC load line and mark the Q point on it. (VBE to be ignored).

  23. For a BJT circuit shown, assume that the 'β' of the transistor is very large and VBE= 0.7 V. The mode of operation.

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