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 length of the lens is

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 length of the lens is (A) (( m +1)2 x / m ) (B) ((m-1)2 x/m) (C) ( mx /( m +1)2) (D) (m x/(m-1)2)

Tardigrade Admin · Accepted Answer

u + v = x m =( v / u ) (1/ v )-(1/ u )=(1/ f )

Q. 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 length of the lens is

$\frac{( m + 1 ) ^{2} x}{m}$

$\frac{( m - 1 ) ^{2} x}{m}$

$\frac{m x}{( m + 1 ) ^{2}}$

$\frac{m x}{( m - 1 ) ^{2}}$

$u + v = x$
$m = \frac{v}{u}$
$\frac{1}{v} - \frac{1}{u} = \frac{1}{f}$

Q. 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 length of the lens is

m(m+1)2x​

m(m−1)2x​

(m+1)2mx​

(m−1)2mx​