476. Compared to a CB amplifier has—

1. 1. Lower input resistance

   
   
   

   2. higher input resistance

   
   
   

   3. Lower current amplification

   
   
   

   4. Higher current amplification
      

   
   
   

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   NA

   Correct Option: D

   NA

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477. A transistor connected in common-base configuration has—

1. 1. A low input resistance and high output resistance

   
   
   

   2. A low input resistance and a low output resistance

   
   
   

   3. A 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: A

   NA

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478. The high resistance of the reverse-biased collector junction is due to the fact that—

1. 1. A small change in collector bias voltage causes a large change in collector current.

   
   
   

   2. A large change in collector bias voltage causes very little change in collector current.

   
   
   

   3. A small change in emitter current causes an almost equal change in collector current.

   
   
   

   4. A small change in emitter bias voltage causes a large change in collector current.
      

   
   
   

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   NA

   Correct Option: B

   NA

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479. In regard semiconductor photodiodes the following statements are mode—
     1. In a typical volt ampere characteristic for a given illumination, the reverse current is almost constant for increasing reverse voltage.
     2. Due to creation of electron hole pairs by incident photons, the essential concentration of majority carriers is much greater than the percentage increase in minority carriers.
     3. The radiation can be considered as a minority carrier injector.
     4. The photo-current is due to drifting of injected carriers.
     Of the four statements, the correct statements are—

1. 1. 2, 4

   
   
   

   2. 1, 2

   
   
   

   3. 2, 3

   
   
   

   4. 1, 3

   
   
   

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   NA

   Correct Option: D

   NA

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480. In regard to the reverse biased pn junction photodiode the following statements are made—
     1. The photon current and the saturation current are in the same direction.
     2. While the photon current is essentially due to minority carriers, the saturation current is due to majority carrier flow.
     3. The number of electron hole pairs due to illumination is proportional to the number of incident photons.
     4. The effect of illumination can be considered as a majority carrier injection.
     Of the four statements, the true statements are—

1. 1. All four

   
   
   

   2. (1) and (2)

   
   
   

   3. (2) and (4)

   
   
   

   4. (1) and (3)

   
   
   

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   NA

   Correct Option: D

   NA

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