56. The magnifying power of a telescope can be increased by

1. 1. Reducing the focal length of the eye piece

   
   
   

   2. Increasing the diameter of the objective

   
   
   

   3. Reducing the focal length of the objective

   
   
   

   4. Increasing the diameter of the eyepiece

   
   
   

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   N/A

   Correct Option: A

   N/A

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57. Optically active substances are those substances which

1. 1. Produce polarized light

   
   
   

   2. Rotate the plane of polarization of polarized light

   
   
   

   3. Produce double refraction

   
   
   

   4. Convert a plane polarized light into circularly polarized light

   
   
   

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1. View Hint View Answer Discuss in Forum

   N/A

   Correct Option: B

   N/A

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58. How for must a girl standing front of a concave spherical mirror of radius 120 cm to see an erect image of her face four times its natural size?

1. 1. 40 cm from the mirror

   
   
   

   2. 45 cm from the mirror

   
   
   

   3. 50 cm from the mirror

   
   
   

   4. 55 cm from the mirror

   
   
   

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1. View Hint View Answer Discuss in Forum

   N/A

   Correct Option: B

   N/A

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59. The plane surface of plano-convex lens of focal lengh f is silvered. It will behave as a

1. 1. Plane mirror

   
   
   

   2. Convex mirror of focal length 2 f

   
   
   

   3. Concave mirror of focal lengh f / 2

   
   
   

   4. None of the above

   
   
   

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1. View Hint View Answer Discuss in Forum

   N/A

   Correct Option: C

   N/A

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60. Laser light is considered to be coherent because it consists of

1. 1. Many wavelengths

   
   
   

   2. Uncoordinated wavelengths

   
   
   

   3. Coordinated waves of exactly the same wavelength

   
   
   

   4. Divergent beams

   
   
   

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1. View Hint View Answer Discuss in Forum

   N/A

   Correct Option: C

   N/A

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