16. 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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1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: B

   NA

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17. 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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18. 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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1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: B

   NA

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19. 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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1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: A

   NA

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20. When a stone is dropped on the surface of still water, the waves produced are

1. 1. Transverse

   
   
   

   2. Longitudinal

   
   
   

   3. Stationary

   
   
   

   4. Partially longitudinal and partially transverse

   
   
   

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1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: D

   NA

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