81. As an object gets closer to the focal point of a converging lens from infinity, its image

1. 1. Becomes smaller

   
   
   

   2. Remains of the same size

   
   
   

   3. Gets farther from the lens

   
   
   

   4. Gets closer to the lens

   
   
   

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   N/A

   Correct Option: C

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82. If the top half of a convex lens is covered with black paper

1. 1. The bottom half of the image will disappear

   
   
   

   2. The top half of the image will disappear

   
   
   

   3. The magnification will reduced to half

   
   
   

   4. The intensity will be reduced to half

   
   
   

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   N/A

   Correct Option: D

   N/A

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83. When light enters from air to water, then its

1. 1. Frequency increases and speed decreases

   
   
   

   2. Frequency is same but the wavelength is smaller in water than in air

   
   
   

   3. Frequency is same but the wavelength is Larger in water than in air

   
   
   

   4. Frequency and wavelength both decreases

   
   
   

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1. View Hint View Answer Discuss in Forum

   N/A

   Correct Option: B

   N/A

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84. When a CD (compact disc used in audio and video systems) is seen in sunlight, Rainbow like colours are seen. This can be explained on the basis of the phenomenon of

1. 1. Reflection and diffraction

   
   
   

   2. Reflection and transmission

   
   
   

   3. Diffraction and transmission

   
   
   

   4. Refraction, diffraction and transmission

   
   
   

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1. View Hint View Answer Discuss in Forum

   N/A

   Correct Option: D

   N/A

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85. An explosion takes place on the surface of moon. An astronaut at some distance from the site of explosion will

1. 1. Observe light and hear sound caused by the explosion

   
   
   

   2. Observe light but not hear sound caused by the explosion

   
   
   

   3. Hear sound but not observe light caused by the explosion

   
   
   

   4. Neither hear sound nor observe light caused by the explosion

   
   
   

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1. View Hint View Answer Discuss in Forum

   N/A

   Correct Option: B

   N/A

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