Light travels in a straight line. This principle is illustrated in a pinhole camera. In this simple device the image of an object is formed on a photographic plate by light passing through a small hole.
In one experiment, 5 cm high image of a tree was obtained on a photo plate placed at a distance of 15 cm from the pin hole. Actual height of the tree is 20 m.
(a) Find the distance of the pinhole from the tree.
(b) How is the size of image affected if the photo plate is moved away from the pinhole?
(c) What will happen if a large hole is made in place of a pin hole?
