486. A transistor is operating in the active region. Under this condition—

1. 1. Both the junctions are forward-biased

   
   
   

   2. Both the junctions are reverse-biased

   
   
   

   3. Emitter-base junction is reverse-biased, and collector-base junction is forward-biased

   
   
   

   4. Emitter-base junction is forward-biased and collector-base junction is reverse-biased

   
   
   

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1. View Hint View Answer Discuss in Forum

   Please refer synopsis.

   Correct Option: D

   Please refer synopsis.

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487. The basic difference between the zener diode and the general diode is—

1. 1. Concentration profile (i.e. doping)

   
   
   

   2. Applied reverse voltage

   
   
   

   3. Applied forward voltage

   
   
   

   4. Data is insufficient

   
   
   

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1. View Hint View Answer Discuss in Forum

   The basic difference between the zener diode and the general diode is concentration profile i.e. doping concentration because the concentration profile is the most deciding parameter for any type of diode.

   Correct Option: A

   The basic difference between the zener diode and the general diode is concentration profile i.e. doping concentration because the concentration profile is the most deciding parameter for any type of diode.

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488. In an Abrupt pn-junction the doping concentrations on the p-side and n-side are N_A = 10¹⁷/cm³ and N_D = 10¹⁶/cm³ respectively. It the pn-junction is reverse biased and total depletion width is 3 µm. The depletion width on p-side will be—

1. 1. 0.3 µm

   
   
   

   2. 0.27 µm

   
   
   

   3. 2.7 µm

   
   
   

   4. None of these

   
   
   

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1. View Hint View Answer Discuss in Forum

   Since the Net charge must be zero
   N_A W_P = N_D W_n
   10¹⁷ × W_P = 10¹⁶ × Wⁿ
   W_n = 10 W_P …(i)
   W_P + W_n = 3 µm …(ii)
   

   from (i) and (ii) WP =	3	µm = 0.27 µm
   	11

   
   

   Correct Option: B

   Since the Net charge must be zero
   N_A W_P = N_D W_n
   10¹⁷ × W_P = 10¹⁶ × Wⁿ
   W_n = 10 W_P …(i)
   W_P + W_n = 3 µm …(ii)
   

   from (i) and (ii) WP =	3	µm = 0.27 µm
   	11

   
   

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489. If the amount of impurity, either p-type or n-type, added to the intrinsic is controlled to part in one million, the conductivity of the sample—

1. 1. Increases by a factor of 10⁶

   
   
   

   2. Increases by a factor of 10³

   
   
   

   3. Decreases by a factor of 10^–3

   
   
   

   4. Is not affected at all

   
   
   

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1. View Hint View Answer Discuss in Forum

   Increases by a factor of 10⁶

   Correct Option: A

   Increases by a factor of 10⁶

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490. In an n-type semiconductor, the concentration of minority carriers mainly depends upon—

1. 1. The doping technique.

   
   
   

   2. The number of donor atoms.

   
   
   

   3. The temperature of the material.

   
   
   

   4. The quality of the intrinisic material, Ge or Si.

   
   
   

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1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: C

   NA

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