Question

The focal length of objective and eye lens of a microscope are `4 cm` and `8 cm` respectively. If the least distance of distinct vision is `24 cm` and object distance is `4.5 cm` from the objective lens, then the magnifying power of the microscope will be
A. `18`
B. 32
C. 64
D. 20

Answer 1

Correct Answer - B
For objective lens `(1)/(f_(o))=(1)/(v_(o))-(1)/(u_(o))`
`implies (1)/(+4)+(1)/(v_(o))-(1)/((-4.5))impliesv_(o)=36cm`
`:. |m_(D)|=(v_(o))/(u_(o))(1+(D)/(f_(e)))=(36)/(4.5)(1+(24)/(8))=32`