Question

A tree, which is 200 m away from the pinhole, produces an image of height 1cm, in a pinhole camera of width 20 cm. Find the height of the tree.

• A. 30 m
• B. 20 m
• C. 10 m
• D. 40 m

Answer 1

The correct option is C 10 m

Given: A tree, which is 200 m away from the pinhole, produces an image of height 1cm, in a pinhole camera of width 20 cm

To find the height of the tree.

Solution:

According to the given criteria,

Object distance from pinhole, $u=200m$

Image distance from the pinhole, $v=20cm=0.2m$

Image height, $h_i=1cm=0.01m$

Let tree height, i.e., object height be $h_o$

For pinhole camera,

$h_i=\frac{v\times h_o}{u}⟹0.01=\frac{0.2\times h_o}{200}⟹h_o=\frac{200\times 0.01}{0.2}=10m$

Hence the height of the tree is 10m.