Ray diagrams

Because light travels in straight lines we can use line diagrams, more usually known as ray diagrams, to describe a ray of light as it travels.

We see luminous objects because some of light they emit enter our eyes.

We see non-luminous objects because some of the rays of light they reflect enter our eyes.

RAY DIAGRAM

NON LUMINOUS OBJECT
LIKE EARTH AND STARS  

(doesn't makes its own light) .

 LUMINOUS OBJECT WHICH MAKES

 ITS OWN LIGHT.