Objects are seen when light is emitted or reflected from them and enters the eye through the pupil, causing the retina to send messages, carried by the nerves, to the brain

Imagine looking at the crayon. The light scattered from the crayon is scattered in all directions. The drawing shows the light that falls upon the eye of the observer. Notice that the image, like that in a pin hole camera, is upside down. The image falls upon the retina where it is converted into a small electrical message that is carried down the optic nerve to the brain. The brain then turns the image upside down so that reality as we know it remains the right way up.

Contents

Light does appear to travel in straight lines
Light can differ in intensity and wavelength
The distinction between reflection and scattering, How images are formed in a mirror
The colour of an object depends on the wavelength of light that it scatters
Self assessment