Question

the focal lengths of a convex lens and concave lens are 10cm and 15cm respectively.Both lenses are kept in contact.An object is placed at a distance of 25cm from this combined lens. determine the position of image of the object​

Answer 1

Explanation:

Given,

f1=+10cm for convex lens

f2=−20cm for concave lens

The focal length of the combination is given by

f1=f21+f21

f1=+10cm1+−20cm1=20cm1

f=+20cm