light is a form of radiation This means that light radiates (spreads out) from its source. In a diagram lines called rays are used to show which way light is going
light travels in straight lines
We can see this if we look at sun beams or laser beams
light transfers energy
Light travels as waves
Light radiates from its source rather as ripples spread across the surface of a pond. However, in the case of light the “ripples” are tiny varying electric and magnetic fields. These “ripples” are very small: about 2000 light waves could fit into 1 millimeter
But some effects of light are best explained by thinking of light as a stream of tiny “energy particles”. Scientists call these particles photons.
Light can travel through empty space
Electric and magnetic “ripples” don’t need a medium to travel through; this is why light form the sun and stars can reach us.
light is the fastest thing there is
The speed of light is about 3,000,000 km/s. nothing can travel faster than this. The speed of light seems to be the universal speed limit
In the second diagram the lamp is an extended (spread out) source of light. This time, the shadow is blurred at the edges this is because each point on the lamp causes a different shadow and they all overlap