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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