1.

A Concave lens of focal length `20 cm` produces an image half in size of the focal object. The distance of the real object isA. `20cm`B. `30 cm`C. `10 cm`D. `60 cm`

Answer» Correct Answer - A
`m=(f)/(f+u)`
`(1)/(2)=(-20)/(-20+u)` or `-20+u=-40`
or `u=-40 +20` or `u=-20cm`.
10cm


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