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 .

Options

A. `(mx)/(m+1)^(2)`
B. `(mx)/(m-1)^(2)`
C. `(m+1)^(2_/m x`
D. `(m-1)^(2)/m x`

Answer

A

Explanation

`u+=xvto(1),v/u=m to(2)`
`1/f=1/u+1/vto(3)`
Solving (1),(2),(3), `f=(mx)/(m+1)^(2)`