Question

An object is placed at the following distances from a convex lens of focal length 15 cm :

(a) 35 cm

(b) 30 cm

(c) 20 cm

(d) 10 cm

Which position of the object will produce : 

(i) a magnified real image ? 

(ii) a magnified virtual image ?

(iii) a diminished real image ?

(iv) an image of same size as the object ?

Answer 1

Here, f =15cm and 2f = 30cm

(i) 20 cm (Because a magnified real image is formed when the object is placed between f and 2f).

(ii) 10cm (Because a magnified virtual image is formed when the object is placed between f and the lens).

(iii) 35cm (Because a diminished real image is formed when the object is placed beyonf 2f).

(iv) 30cm (Because an image of same size as the object is formed when the object is placed at 2f).