Question

An object is placed at a distance 20 cm from a convex lens of focal length 10 cm. Find the image distance and nature of the image.

Answer 1

u = -20 cm

f = 10 cm

\(\frac 1f = \frac 1v - \frac 1u\)

\(\frac 1v = \frac 1f + \frac 1u\)

\(\frac 1v = \frac 1{10} + \frac1{(-20)}\)

\( \frac 1v = \frac 1{10} - \frac 1{20}\)

\(\frac 1v = \frac {2-1}{20}\)

\( \frac 1v = \frac 1{20}\)

\(\Rightarrow v = 20 cm\)

Nature of the image real enlarged and inverted image.