Question

A telescope has an objective of focal length `50 cm` and eye piece of focal length `5 cm`. The least distance of distinct vision is `25 cm`. The telescope is focussed for distinct vision on a scale `200 cm` away from the objective. Calculate
(i) the separation between objective and eye piece
(ii) the magnification produced.
A. 75 cm
B. 60 cm
C. 71 cm
D. 74 cm

Answer 1

Correct Answer - C
(c ) For objective,
`1/v_(o)-1/(-200)=1/50`
`therefore v_(o)=200/3cm`
For eye-pieces,
`1/(-25)-1/((-u_(e)))=1/5`
`therefore u_(e)=25/6`
Therefore, seperation between objecctive and eye-piece,
`L=v_(o)+u_(e)=200/3+25/6=425/6=71 cm`