A straight line on which light travels is called a light ray.
Usually light does not travel on a single ray , but on a bundle of rays, called a beam.
We can distinguish between parallel beams, diverging and converging beams.
Parallel beam
Diverging beam
Converging beam
Most objects do not produce light of their own.
They reflect the light that falls on them and our eyes see the reflected light.
So the color of an object depends on the color of light that it reflects back into our eyes.
The colors we see depend on the sort of light that falls on objects.
Yellow sodium street lights make some colors very bright.
These colors are used in safety equipment and clothing
to make them show up clearly at night.