The length of tube of a microscope is 10 cm . The focal length of the objective and eye lens are 0.5 cm and 1.0 cm . The magnifying power of microscope is about ?

1 ) The length of tube of a microscope is 10 cm . The focal length of the objective and eye lens are 0.5 cm and 1.0 cm . The magnifying power of microscope is about : -

A ) 221 ,                                                     B ) 500 ,

C ) 891 ,                                                     D ) None of these ,

Correct Answer : -   B ) 500 ,

Solution : -

So , it is compound microscope .

M  =  ( L D )  /  ( fo fe ) .

∴ L = length of tube = 10 cm ,

∴ fo = 0.1 cm  ,   fe = 1 cm  .

∴ D = least distance of distinct vision = 25 cm .

So ,  M = (10 x 25 ) / (0.5 x 1 )  =  500  ,  Answer .

 

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2 ) A compound microscope has a magnifying power of 100 when the image is formed at infinity . The objective has a focal length of 0.5 cm and the tube length is 6.5 cm . Find the focal length of the eye piece : -

A ) 2 cm ,                                                   B ) 8.4 cm ,

C ) 11 cm ,                                                 D ) None of these ,

Correct Answer : -   A ) 2 cm ,

Solution : -

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