Magnification produced by astronominal telescope for normal adjustment is 10 and length of telescope is 1.1m. The magnification when the image is formed at least distance of distinct vision `(D = 25cm)` is-

Options

A. 6
B. 14
C. 16
D. 18

Answer

B

Explanation

Magnification, `M=(f_(o))/(f_(e ))=10` or `f_(o)=10 f_(e )`
Given, `f_(e )+f_(o)=1.1 m`
`f_(e )+10 f_(e )=1.1xx100 cm`
`11f_(e )=110`
`f_(e )=10`
Magnification least distance of distinct vision
`M_(D)=(f_(o))/(f_(e ))(1+(f_(e ))/(D))=10(1+(10)/(25))=10((35)/(25))=14`