An object is placed at a distance of 15 cm from a concave lens of focal length 30 cm. List four characteristic (nature, position, etc.) of the image formed by the lens.

The focal length of the lens(f), the image distance(v) and the object distance(u) are related as follows:

1/f = (1/v) – (1/u)

Here, focal length(f) = 15cm

Object distance(u) = – 30cm

Therefore, finding the image distance(u) using the above mentioned formula:

v= -10cm

From this we can get to know the important characteristics of the image:

1. Image is erect/upright.

2. Image is virtual.

3.Image is reduced in size.

4.Image is formed at a distance of 10 cm from the optical centre and on the same side in which the object is placed.