1.

The focal length of objective and eye lens of a astronomical telescope are respectively `2m` and `5 cm` . Final image is formed at `(i)` least distance of distinct vision `(ii)` infinity. The magnifying power in both cases will beA. `-48,-40`B. `-40, -48`C. `-40, 48`D. `-48, 40`

Answer» Correct Answer - A
When the final image is at the least distance of distinct vision, then
`m=(f_(o))/(f_(e))(1+(f_(e))/(D))=(200)/(5)(1+(5)/(25))=(200xx6)/(5xx5)=-48`
When the final image at inifinity , then
`m=(-f_(o))/(f_(e))=(200)/(5)=-40`


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