Question

The optical system shown in the Figure consists of two lenses, of focal lengths f₁ = +12 cm and f₂ = -32 cm, separated by a distance L = 22 cm. A luminous object with a height of 2.4 cm is placed 18 cm in front of the first lens. Find the position and the height of the final image. 

Answer 1

Ignoring lens 2 and taking p₁ = 18 cm we get

Thus, lens 1 produces a real inverted magnified image, which is to the right of lens 2. Now ignoring lens 1 and taking p₂ = -(36 cm-22 cm)= -14 cm we get

Thus, the system produces a real inverted magnified image 24.89 cm to the right of lens 2 with height = (3.55)(2.4 cm) = 8.53 cm.