Question

A convex (converging) lens produces a real, inverted image of an object that is magnified 2.20 times when the object is 43.0 cm from the lens. What is the focal length of the lens? (cm)

Answer 1

Answer:29.56 cm

Explanation:

Given

magnification is 2.2

Object distance(u)=43 cm

and we know

$m=-\frac{v}{u}$

$2.2=-\frac{v}{-43}$

$v=43\times 2.2=94.6 cm$

And focal length of convex lens is given by

$\frac{1}{f}=\frac{1}{v}+\frac{1}{u}$

$\frac{1}{f}=\frac{1}{94.6}+\frac{1}{43}$

f=29.56 cm