141. The frequencies of X - rays, y-rays and ultraviolet rays are respectively a, b and c then

1. 1. a < b, b > c

   
   
   

   2. a > b, b > c

   
   
   

   3. a > b, b < c

   
   
   

   4. a < b, b < c

   
   
   

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   NA

   Correct Option: A

   NA

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142. There are three wavelengths 10⁷ m, and 10^-10 m, and 10^-7 m. Find their respective names

1. 1. X - rays, Visible rays, Radio waves

   
   
   

   2. Radio waves, X-rays, Visible rays

   
   
   

   3. Visible rays, Radio wave, X-rays

   
   
   

   4. None of the above

   
   
   

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   NA

   Correct Option: B

   NA

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143. Consider the following parts of spectra
     1. Visible
     2. Infrared
     3. Ultraviolet
     4. Microwave
     Which one of the following is the correct sequence in which their wavelength increase ?

1. 1. 4 - 3 - 1 - 2

   
   
   

   2. 4 - 1 - 2 - 3

   
   
   

   3. 3 - 2 - 1 - 4

   
   
   

   4. 3 - 1 - 2 - 4

   
   
   

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   NA

   Correct Option: D

   NA

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144. Radar waves are sent towards a moving aeroplane and the reflected waves are received. When the aeroplane is moving towards the radar, the wavelength of then wave

1. 1. Increases

   
   
   

   2. Decreases

   
   
   

   3. Remains the same

   
   
   

   4. Sometimes increases of decreases

   
   
   

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   NA

   Correct Option: B

   NA

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145. If two waves of amplitude a produce a resultant wave of amplitude a, the n the phase difference between them is

1. 1. 60°

   
   
   

   2. 90°

   
   
   

   3. 120°

   
   
   

   4. 180°

   
   
   

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   NA

   Correct Option: C

   NA

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