Height of an object h1 = 5 cm

Object distance u = – 27 cm

Focal length = – 18 cm

Height of an image h1 = ?

Image distance u = ?

From the formula :

⇒ 1/u + 1/v = 1/f

⇒ 1/(-27) + 1/v = 1/(-18)

⇒ 1/v = 1/18 + 1/27

⇒ - (3+2)/ 54

⇒ -1/54

⇒ v = –54 cm

Therefore, screen should be placed at a distance of 54 cm from the screen.

m = h₂/h₁ = - v/u

⇒ h₂/7 = -54/-27

⇒ h₂/7 = 2

⇒ h₂ = 14 cm

Thus, the height of the image formed is 14 cm and is real and inverted in nature.