Light comes from natural sources like the sun or fire, and artificial sources like light bulbs. Light travels in a straight line and can pass through some materials, but is blocked by others causing shadows. Objects can either reflect light by bouncing it off their surface, or absorb light. Reflection occurs when light hits a surface and changes direction, either in the same direction for smooth surfaces, or many directions for rough surfaces. Light can pass through transparent materials but changes speed and direction when moving between different materials like air and water, which is called refraction. White light can be refracted and separated into the colors of the visible spectrum.

2. Light
 We need light to see every thing around us.
 Light comes from natural sources like sun or fire
 Light comes form artificial sources like a bulb or a
computer screen

3. The properties of light
 Light travels in a straight line from the source to the
objects.
 It ca travel in any direction
 It can pass through some materials

4.  But some materials block light. When this happens, a
SHADOW appears

5.  Some objects reflect light. When light hits these
objects, it bounces off (rebotar) and changes direction

6. Mateials and light

12. Light reflection
 Opaque objects can reflect light
 When light hits the surface of these materials it
changes the direction
 When light shines on a smooth surface all the rays are
reflected in the same direction. This is called specular
reflection

13.  When light shines on rough or irregular surfaces all the
rays are reflected in different directions. This is called
diffuse reflection

14. Light refraction
 Light can pass through transparent materials but at
different speeds.
 Light speed in space 300,000 km per second
 It travels more slowly through air and very slowly
through water

16.  When light passes from one transparent substance (air)
to another (water) it changes the velocity and the
direction
 This is called refraction

17. Colour
 When WHITE light passes throug a glass prism it is
refractes into a spectrum of seven colours