A 10 cm tall object is placed perpendicular to the principal axis

• Reflection & Refraction (C10)

A 10 cm tall object is placed perpendicular to the principal axis of a convex lens of focal length 12 cm. The distance of the object from the lens is 18 cm. Find the nature, position and size of the image formed.

Answer

1/v − 1/u = 1/f

∴ 1/v = 1/f + 1/u

∴ 1/v = 1/12 + 1/(−18)

∴ v = 36 cm

m = v/u = h'/h

⇒ 36/(−18) = h'/10

⇒ h' = −20 cm (size of the image)

Nature of image - Real and inverted