The focal lengths of the objective and the eyepiece of a compound microscope are 1 cm and 5 cm respectively. An object is placed at a distance of 1.1 cm from the objective. For getting the final image at infinity, the distance between the two lenses, should be

Options

A. 12 cm
B. 13 cm
C. 14 cm
D. 16 cm

Answer

D

Explanation

`u_(o) = -1.1 cm, f_(o) =1cm`
For the objective, `(1)/(v_(o)) -(1)/(u_(o))=(1)/(f_(o))`
`therefore (1)/(v_(o))=(1)/(u_(o))+(1)/(f_(o))= -(1)/(1.1)+(1)/(1)`
` therefore (1)/(v_(o))=(-1+1.1)/(1.1)=(1)/(11)`
`therefore v_(o)=11 cm`
For getting the final at infinity, the image formed by the objective must be at the principal focus of the eyepiece.
`therefore` The distance between the two lenses
`=v_(o)+f_(e)=11+5=16 cm`