Question

An object is kept at a distance of 30 cm from of a convex lens of focal length 20 cm. Calculate the
image distance and state the characteristics of image formed.​

Answer 1

For convex lens:-

Object distance, u = - 30 cm

Focal length, f = 20 cm

By lens formula:-

$\frac{1}{f} = \frac{1}{v} - \frac{1}{u} \\ \\ \frac{1}{20} = \frac{1}{v} - \frac{1}{ - 30} \\ \\ \frac{1}{20} = \frac{1}{v} + \frac{1}{30} \\ \\ \frac{1}{v} = \frac{1}{20} - \frac{1}{30} \\ \\ \frac{1}{v} = \frac{3 - 2}{60} \\ \\ \frac{1}{v} = \frac{1}{60} \\ \\ v = 60 \: cm$

The image will be formed at 60 cm on right side of lens.

Nature of image is Real and Inverted.

Hope it helps.