Light , Characteristics & Light Behaviors 4th Grade Standard - S4P1a

Source of Light Light is all around us.  The Sun is a ball of burning hot gases that gives off a very bright light. Light travels through the air in straight lines. If it didn't there wouldn't be any shadows.

The only way we can see an object is if rays of light hit the object and it then reaches our eyes. This is why we can’t see things in the dark. The objects are still there but there is no light to reveal them.

The moon does not produce its own light The moon does not produce its own light. Moonlight is sunlight that has bounced off the moon! When light hits a surface, some of it bounces off or is reflected.

Light can pass through transparent objects like glass but cannot pass through opaque objects like wood. Things look strange underwater, because light travels from them in a different way. Light moves more slowly through water than it moves through air. As the beam of light enters the water, it slows down and bends. As it re-enters the air the light beam speeds up and bends back again. This is called refraction.

Transparent materials allow light to travel through them Transparent materials allow light to travel through them.  We can see clearly through transparent materials like water and glass.

You tell me… What else can you see through? What can you think of that is transparent? Make a list of transparent objects with a partner

Share out…

Opaque objects do not let light travel through them Opaque objects do not let light travel through them.  These objects create shadows on a sunny day.

You tell me… What else can you think of that is opaque? Make a list of opaque objects with a partner.

Share out…

Translucent materials allow light to come through but we cannot see through it. 

You tell me… What else can you think of that is translucent? Make a list of translucent objects with a partner.

Share out…

Which is transparent, opaque and translucent?

Light and Reflection Reflection occurs when light bounces off objects. How much reflection depends upon how even the surface is.  

If the surface is rough, the light scatters.

If the surface is smooth and flat, the light will bounce off it at equal angles.  

Let’s Practice Let’s see how light reflects off a mirror.

Lenses Refraction occurs because light bends.  A lens is a piece of transparent material.  It is usually made of glass and has at least one curved surface. Look at the convex and concave lenses below.

Two types of lenses

The curved surface/surfaces of a lens bends the light The curved surface/surfaces of a lens bends the light.  Notice the paths of light of the convex and concave lenses shown below.

Convex Lense

Concave Lense