In Galilean telescope, if the powers of an objective and eye lens are respectively `+1.25D` and `-20 D`, then for relaxed vision, the length and magnification will be

Options

A. `21.25 cm ` and `16`
B. `75 cm` and 20
C. `75 cm` and `16`
D. `8.5 cm` and `21.25`

Answer

C

Explanation

`f_(o)=(1)/(1.25)=0.8m`and `fe=(1)/(-20)=0.05m`
`:. |L_(oo)|=|f_(o)|-|f_(e)|=0.8-0.005=0.75m=75cm`
and `|m_(oo)|=(f_(o))/(f_(e))=(0.8)/(0.05)=16`