Draw ray diagrams to represent the nature, position and relative size of the lens for the object placed:
a) at `2F_(1)`,
b) between `F_(1)` and the optical center O of the lens.
Which of the above two cases shows the use of convex lens as a magnifying glass? Give reasons for your choice.

Explanation

(i) When the object AB is placed at `2F_(1)`, the image A'B' formed at `2F_(2)` is real, inverted and of same size as the object, as shown in the ray diagram in Fig.

(ii) When the object AB lies between `F_(1)` and optical centre O of convex lens, the image A'B' is formed on the same side of the lens as the object. The image is virtual, erect and magnified as shows in the ray diagram