Railways General Science & Technology Semiconductor Electronics Sample Paper

done Semiconductor Electronics Sample Test Paper-12 Total Questions - 20    [Download]

• question_answer1)
  Electric conduction in a semiconductor takes place due to
  A)
   Electrons only
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  B)
   Holes only
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  C)
   Both electrons and holes
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  D)
   Neither electrons nor holes
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• question_answer2)
  Let \[{{n}_{p}}\] and \[{{n}_{e}}\] be the number of holes and conduction electrons in an extrinsic semiconductor. Then
  A)
   \[{{n}_{p}}>{{n}_{e}}.\]       
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  B)
   \[{{n}_{p}}={{n}_{e}}.\]
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  C)
   \[{{n}_{p}}<{{n}_{e}}.\]       
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  D)
   \[{{n}_{p}}\ne {{n}_{e}}.\]
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• question_answer3)
  If the two ends of a p-n junction are joined by a wire
  A)
   There will not be a steady current in the circuit
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  B)
   There will be a steady current from the n-side to the p-side
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  C)
   There will be a steady current from the p-side to the n-side
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  D)
   There may or may not be a current depending upon the resistance of the connecting wire
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• question_answer4)
  In a transistor
  A)
   The emitter has the least concentration of impurity
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  B)
   The collector has the least concentration of impurity
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  C)
   The base has the least concentration of impurity
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  D)
   All the three regions have equal concentrations of impurity
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• question_answer5)
  What is the resistivity of a pure semiconductor at absolute zero?
  A)
   Zero                
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  B)
          Infinity
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  C)
   Same as that of conductors at room temperature
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  D)
   Same as that of insulators at room temperature
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• question_answer6)
  Temperature coefficient of resistance of semiconductor is
  A)
   Zero                
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  B)
   Constant
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  C)
   Positive
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  D)
   Negative
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• question_answer7)
  In a half wave rectifier, the r. m. s. value of the A.C. component of the wave is
  A)
   Equal to d. c. value       
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  B)
   More than d. c. value
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  C)
   Less than d. c. value
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  D)
   Zero
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• question_answer8)
  Zener diode is used for
  A)
   Amplification    
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  B)
   Rectification
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  C)
   Stabilisation     
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  D)
   All of the above
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• question_answer9)
  In reverse biasing
  A)
   Large amount of current flows
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  B)
   Potential barrier across junction increases
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  C)
   Depletion layer resistance decreases
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  D)
   No current flows
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• question_answer10)
  The main difference between voltage and power amplifiers is that
  A)
   Power amplifier handles current
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  B)
   Power amplifier handles large voltage
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  C)
   Power amplifier handles large power
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  D)
   None of the above
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• question_answer11)
  In a transistor:
  A)
   Both emitter and collector have same length
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  B)
   Length of emitter is greater than that of collector
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  C)
   Length of collector is greater than that of emitter
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  D)
   Any one of emitter and collector can have greater length
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• question_answer12)
  A d. c. battery of V volt is connected to a series combination of a resistor R and an ideal diode D as shown in the figure below. The potential difference across R will be
  A)
   2V when diode is forward biased
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  B)
   Zero when diode is forward biased
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  C)
   V when diode is reverse biased
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  D)
   V when diode is forward biased
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• question_answer13)
  The intrinsic semiconductor becomes an insulator at
  A)
   \[0{}^\circ C\]             
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  B)
   0 K
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  C)
   300 K  
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  D)
   \[-100{}^\circ C\]
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• question_answer14)
  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
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  B)
   They move across the junction by the potential difference
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  C)
   hole concentration in p-region is more as compared to n-region
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  D)
   All the above
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• question_answer15)
  In a semiconductor, the concentration of electrons is \[8\times {{10}^{14}}/c{{m}^{3}}\] and that of the holes is \[5\times {{10}^{12}}c{{m}^{3}}.\] The semiconductor is
  A)
   p-type 
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  B)
   n-type
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  C)
   Intrinsic
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  D)
   pnp type
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• question_answer16)
  In extrinsic semiconductors
  A)
   The conduction band and valence band overlap
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  B)
   The gap between conduction band and valence band is more than 16 eV
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  C)
   The gap between conduction bands mid valence band is near about 1 eV
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  D)
   The gap between conduction band and valence band will be 100 eV and more
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• question_answer17)
  Function of rectifier is
  A)
   To convert ac into dc
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  B)
   to convert dc into ac
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  C)
   Both [a] and [b]
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  D)
   None of these
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• question_answer18)
  An oscillator is nothing but an amplifier with
  A)
   Positive feedback
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  B)
   negative feedback
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  C)
   Large gain        
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  D)
   no feedback
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• question_answer19)
  To obtain P-type Si semiconductor, we need to dope pure Si with
  A)
   Aluminium       
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  B)
   Phosphorous
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  C)
   Oxygen
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  D)
   Germanium.
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• question_answer20)
  In a fall wave rectifiers, input ac current has a frequency 'v'. The output frequency of current is
  A)
   v/2                  
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  B)
   v
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  C)
   2v                   
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  D)
   none of these
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