Answer to Question #162604 in Optics for Fletcher

Question

The image of a real object in a diverging lens of focal length 10cm is formed 4cm from the lens. Find the object distance and the magnification. Draw a sketch to illustrate the formation of the image.

Answer 1

Answer

f=10cm

v=4cm

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

the object distance

$=>u=\frac{vf}{v-f}\\=\frac{4\times(10)}{4-20}\\=-2.5cm$

the magnification

$m=\frac{v}{u}=\frac{4}{-2.5}=-1.6$