Question

A magnifying lens has a focal length of 100mm. An object whose size is 16mm, is placed at some distance from lens so that the image is formed at a distance of 25cm infront of the lens. What is the size of image (in cm)

Answer 1

Answer:

f=100mm 

h1=16mm 

v=−25cm=−250mm 

v1−u1=f1 

−2501−u1=1001 

u1=−5007 

u=−71.4mm=−7.14cm.

Distance between object and lens is 7.14cm.

The object should be placed at the focus so that the image is formed at infinity.

So, u=−100mm=−10cm 

The object should be placed 10cm in front of the lens.