Question

A convex lens forms all real and inverted image of finite size at a distance of 50cm from it .where is the object placed in front of the lens ?give all possible positions of the object stating reason in each case?

Answer 1

the object may be 1)beyond f2

2)at f2

3)b/w f and f2

4)at f

5)at infinity

since the image formed when object is kept b/w o and f is virtual and erect

thus, all cases other than this are possible

Answer 2

Answer: Beyond 2F1 , At 2F1 , between 2F1 and F1

Explanation:When object is at infinity it forms point sized image. So its not finite sized.

When object is Beyond 2F1 , At 2F1 , between 2F1 and F1 , it can form finite sized images.

When object is at F1 the image is formed at infinity and when the object is between F1 and Optical Centre of the lens it will form a Vitual image. Its given that the image is formed at 50 cm from the lens and also that its real and inverted. So these two are not possible.