A concave lens of focal length f produces an image (1 / x) of the size of the object. The distance of the object from the lens is

Question

A concave lens of focal length f produces an image (1 / x) of the size of the object. The distance of the object from the lens is (A) (x-1) f (B) (x+1) f (C)  (x-1) / x f (D)  (x+1) / x f

Tardigrade Admin · Accepted Answer

m=(f/f+u) For virtual image m=+(1/x) +(1/x)=(-f/-f+u) u=-f(x-1)

Q. A concave lens of focal length $f$ produces an image $(1/ x)$ of the size of the object. The distance of the object from the lens is

$(x - 1) f$

$(x + 1) f$

${(x - 1) / x} f$

${(x + 1) / x} f$

$m = \frac{f}{f + u}$
For virtual image $m = + \frac{1}{x}$
$+ \frac{1}{x} = \frac{- f}{- f + u}$
$u = - f (x - 1)$

Q. A concave lens of focal length f produces an image (1/x) of the size of the object. The distance of the object from the lens is

(x−1)f

(x+1)f

{(x−1)/x}f

{(x+1)/x}f