Question

In a pinhole camera, the image of height 6 cm is formed at a distance of 10 cm. If the object is situated at a distance of 5 cm, the height of the object is:

• A. 3 cm
• B. 6 cm
• C. 1.5 cm
• D. 2 cm

Answer 1

The correct option is A

3 cm

Magnification can be related to object distance u and image distance v
Given, $u=5cm$ and $v=10cm$
Magnification, $m=\frac{v}{u}=\frac{10}{5}=2$
Height of image $=6cm$
$\frac{\text{Height of image}}{\text{Height of object}}=\text{Magnification}=2$
Hence, height of object $=\frac{6}{2}=3cm$