12th Class Physics Semiconducting Devices Question Bank

done MCQs - Semiconductor Electronics: Materials, Devices and Simple Circuits Total Questions - 15

• question_answer1)
  In an n-type silicon, which of the following statement is true:
  A)
  Electrons are majority carriers and trivalent atoms are the dopants. done clear
  B)
  Electrons are minority carriers and pentavalent atoms are the dopants. done clear
  C)
  Holes are minority carriers and pentavalent atoms are the dopants. done clear
  D)
  Holes are majority carriers and tiivalent atoms are the dopants. done clear
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• question_answer2)
  Carbon, silicon and germanium have four valence electrons each. These are characterised by valence and conduction bands separated by energy band gap respectively equal to \[{{({{E}_{g}})}_{C,}}{{({{E}_{g}})}_{Si}}\] and \[{{({{E}_{g}})}_{Ge}}\] Which of the following statements is true?
  A)
  \[{{({{E}_{g}})}_{Si}}<{{({{E}_{g}})}_{Ge}}<{{({{E}_{g}})}_{C}}\] done clear
  B)
  \[{{({{E}_{g}})}_{C}}<{{({{E}_{g}})}_{Ge}}>{{({{E}_{g}})}_{Si}}\] done clear
  C)
  \[{{({{E}_{g}})}_{C}}>{{({{E}_{g}})}_{Si}}>{{({{E}_{g}})}_{Ge}}\] done clear
  D)
  \[{{({{E}_{g}})}_{C}}={{({{E}_{g}})}_{Si}}={{({{E}_{g}})}_{Ge}}\] done clear
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• question_answer3)
  The conductivity of a semiconductor increases with increase in temperature because
  A)
  number density of free current carriers increases. done clear
  B)
  relaxation time increases. done clear
  C)
  both number density of carriers and relaxation time increase. done clear
  D)
  number density of current carriers increases: relaxation time decreases but effect of decrease in relaxation time is much less than the increase in number density. done clear
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• question_answer4)
  Hole is
  A)
  an anti-particle of electron. done clear
  B)
  a vacancy created when an electron leaves a covalent bond. done clear
  C)
  absence of free electrons. done clear
  D)
  an artificially created particle. done clear
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• question_answer5)
  Semiconductors behave like insulators at ____
  A)
  \[{{0}^{o}}C\] done clear
  B)
  0 K done clear
  C)
  273 K done clear
  D)
  None of the above done clear
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• question_answer6)
  When the conductivity of a semiconductor is due to rupture of its covalent bond only then the semiconductor is called
  A)
  Intrinsic done clear
  B)
  Extrinsic done clear
  C)
  Donor done clear
  D)
  acceptor done clear
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• question_answer7)
  Tetra valent semiconductor is to be doped with __ valent element to achieve ___ type extrinsic semiconductor.
  A)
  penta, n done clear
  B)
  tri, p done clear
  C)
  penta, p done clear
  D)
  both [a] and [b] done clear
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• question_answer8)
  In an unbiased p-n junction, holes diffuse from the p-region to n-region because
  A)
  free electrons in the n-region attract them. done clear
  B)
  they move across the junction by the potential difference. done clear
  C)
  hole concentration in p-region is more as compared to n-region. done clear
  D)
  All the above. done clear
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• question_answer9)
  When a forward bias is applied to a p-n junction, it
  A)
  raises the potential barrier. done clear
  B)
  reduces the majority carrier current to zero. done clear
  C)
  lowers the potential barrier. done clear
  D)
  None of the above done clear
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• question_answer10)

  In Figure, \[{{V}_{\operatorname{o}}}\] is the potential barrier across a p-n junction, when no battery is connected across the junction

  A)
  1 and 3 both correspond to forward bias of junction done clear
  B)
  3 corresponds to forward bias of junction and 1 corresponds to reverse bias of junction done clear
  C)
  1 corresponds to forward bias and 3 corresponds to reverse bias of junction. done clear
  D)
  3 and 1 both correspond to reverse bias of junction. done clear
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• question_answer11)

  In Figure, assuming the diodes to be ideal,

  A)
  \[{{\operatorname{D}}_{1}}\] is forward biased and \[{{\operatorname{D}}_{2}}\] is reverse biased and hence current flows from A to B done clear
  B)
  \[{{\operatorname{D}}_{2}}\] is forward biased and \[{{\operatorname{D}}_{1}}\] is reverse biased and hence no current flows from B to A and vice versa. done clear
  C)
  \[{{\operatorname{D}}_{1}}\] and \[{{\operatorname{D}}_{2}}\] are both forward biased and hence current flows from A to B. done clear
  D)
  \[{{\operatorname{D}}_{1}}\] and \[{{\operatorname{D}}_{2}}\] are both reverse biased and hence no current flows from A to B and vice versa. done clear
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• question_answer12)

  A 220 V A.C. supply is connected between points A and B in Figure. What will be the potential difference V across the capacitor?

  A)
  220 V done clear
  B)
  110 V done clear
  C)
  0 V done clear
  D)
  220\[\sqrt{2}\] V done clear
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• question_answer13)

  The output of the given circuit in Figure

  A)
  would be zero at all times. done clear
  B)
  would be like a half wave rectifier with positive cycles in output. done clear
  C)
  would be like a half wave rectifier with  negative cycles in output. done clear
  D)
  would be like that of a full wave rectifier. done clear
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• question_answer14)

  In the circuit shown in Figure, if the diode forward voltage drop is 0.3 V, the voltage difference between A and B is

  A)
  1.3 V done clear
  B)
  2.3 V done clear
  C)
  0 V done clear
  D)
  0.5 V done clear
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• question_answer15)
  Which one of the following diagrams depicts the proper flow or electrons and holes in a forward biased p-n junction diode?
  A)
  done clear
  B)
  done clear
  C)
  done clear
  D)
  done clear
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