Question

A convex lens of focal length `f` is placed somewhere in between an object and a screen. The distance between the object and the screen is `x`. If the numerical value of the magnification produced by the lens is `m`, then the focal lnegth oof the lens is .
A. `(mx)/((m+1)^(2))`
B. `(mx)/((m-1)^(2))`
C. `((m+1)^(2))/(m)x`
D. `((m-1)^(2))/(m)x`

Answer 1

Correct Answer - A
`(v)/(-u)=-m` and `v+uimpliesu=(x)/(1+m)`
`(1)/(f)=(1)/(v)=(1)/(u)impliesf=(mx)/((m+1)^(2))`