Answer to Question #2944 in Optics for dave

Question

A converging lens has a focal length of 25.5 cm. If it is placed 72.5 cm from an object, at what distance from the lens will the image be? What is the magnification of the lens?

Answer 1

In this case, we can write the formula of lens as

$\frac {1}{F}=\frac {1}{d} + \frac {1}{f} (1)$

where F the focal length, d is the object distance, f is the image distance

Using (1) we got

$f=\frac {Fd}{d-F} (2)$

f=39.3 cm

The magnification of the lens is given by formula

$k=\frac {f}{d} (3)$

k=0.54

Answer

39.3 cm, 0.54