A man 1.5m tall is standing 3m in front of a pinhole camera whose distance between the hole and the screen is…

Analyze the question

A pinhole camera forms an inverted real image on the screen. The question gives:

• Object height (h_o) = 1.5 m
• Object distance (u) = 3 m
• Image distance (v) = 0.1 m (hole to screen)
• Image height (h_i) = ?

Concept

A pinhole camera works by similar triangles. The ray from the top of the object passes straight through the hole and lands on the screen. This gives the magnification relation:

h_i / h_o = v / u

Solution

h_i = h_o × (v / u)

h_i = 1.5 × (0.1 / 3)

h_i = 1.5 × 0.0333...

h_i = 0.05 m

Answer

The image is 0.05 m tall (and inverted), which matches option A.

Tip

For a pinhole camera, remember: image size / object size = image distance / object distance. Here the man is 30 times farther from the hole than the screen is (3 ÷ 0.1 = 30), so the image is 30 times smaller: 1.5 ÷ 30 = 0.05 m. In JAMB, a quick ratio like this saves valuable time.