471. In a PNP transistor, electons flow—

1. 1. Out of the transistor at the collector and base leads

   
   
   

   2. Into the transistor at the emitter and base leads

   
   
   

   3. Into the transistor at the collector and base leads

   
   
   

   4. Out of the transistor at the emitter and base leads
      

   
   
   

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   NA

   Correct Option: C

   NA

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472. In an intrinsic semiconductor—

1. 1. With increasing temperature the density of electron hole pairs increases

   
   
   

   2. The resistivity increases per degree rise in temperature

   
   
   

   3. At low temperatures, well above 0 K, electrons move into the valence band

   
   
   

   4. Holes along with electrons carry current in the conduction band
      

   
   
   

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   In an intrinsic semiconductor with increasing temperature the density of electron hole pairs increases.
   

   Correct Option: A

   In an intrinsic semiconductor with increasing temperature the density of electron hole pairs increases.
   

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473. In a metal—

1. 1. The electrical conduction is by electrons and holes

   
   
   

   2. With rise in temperature, the conductivity decreases

   
   
   

   3. The conduction band is empty

   
   
   

   4. There is a small energy gap between the two bands
      

   
   
   

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   NA

   Correct Option: B

   NA

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474. The input and output signals of a common-emitter amplifier are—

1. 1. Always equal

   
   
   

   2. Out of phase

   
   
   

   3. Always negative

   
   
   

   4. In phase

   
   
   

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   NA

   Correct Option: B

   NA

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475. A transistor, when connected in common-emitter mode, has—

1. 1. A high inputresistance and a low output resistance

   
   
   

   2. A medium input resistance and a high output resistance

   
   
   

   3. Very low input resistance and a low output resistance

   
   
   

   4. A high input resistance and a high output resistance

   
   
   

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   NA

   Correct Option: B

   NA

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