61. Which of the following is a sources of man-made noise?

1. 1. Fluorescent tubes

   
   
   

   2. Automobile ignition

   
   
   

   3. Electric motors

   
   
   

   4. All of these

   
   
   

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   NA

   Correct Option: D

   NA

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62. Let X and Y be has stationary independent random variables uniformly distributed in the ranges (– 1, 1) and (– 2, 1) respectively. If Z = X + Y, then the probablity that Z < – 2 is—

1. 1. 0

   
   
   

   2. 1

      6

   
   
   

   3. 1

      3

   
   
   

   4. 1

      12

   
   
   

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   Given, random variable x lies in the range (– 1, 1) and y lies in the range (– 2, 1) i.e.
   
   then P(z ≤ – 2) = 0

   Correct Option: A

   Given, random variable x lies in the range (– 1, 1) and y lies in the range (– 2, 1) i.e.
   
   then P(z ≤ – 2) = 0

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63. Which of the following is a source of atmospheric noise?

1. 1. Automobile ignition

   
   
   

   2. Solar noise

   
   
   

   3. Lighting discharges in thunderstorms

   
   
   

   4. Induction motor noise

   
   
   

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1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: C

   NA

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64. Shot noise is vacuum tube is—

1. 1. Directly proportional to trans-conductance

   
   
   

   2. inversely proportional to trans-conductance

   
   
   

   3. inversely proportional to current

   
   
   

   4. None of the above

   
   
   

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1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: B

   NA

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65. For an ideal receiver, noise figure should be—

1. 1. 0·5

   
   
   

   2. 1·0

   
   
   

   3. 10

   
   
   

   4. 100

   
   
   

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1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: B

   NA

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