State the principle of pinhole camera

A Pinhole Camera:

A pinhole camera works on the principle that light travels in straight lines.

The pinhole camera consists of a closed box having a small pinhole in the front and a translucent screen made of butter paper at the back which acts as a screen to receive the image of an object. The pinhole camera is used to view the images of various objects like trees and buildings, etc. 

Formation of image in a pinhole camera:

A ray of light coming from the top point A of the tree passes through the pinhole in a straight line to form an image at point A’ on the screen. Another ray of light coming from the bottom B of the tree also passes through the pinhole in a straight line to form an image at point B’ on the screen. Each point on the tree AB forms its corresponding image on the screen between points A’and B’. The image A’B’ of the tree AB is produced on the screen.

The working of a pinhole camera illustrates the property that light travels in straight lines.

An inverted image is formed in a pinhole camera because the light rays coming from the top and bottom of the object intersect at the pinhole.

Characteristics of the image formed by a pinhole camera:

1. The image in a pinhole camera is real and inverted.
2. The image in a pinhole camera is of the same colour as the object.
3. The image in a pinhole camera can be smaller than the object, equal to the object or bigger than the object depending on the distance of object from the pinhole camera.