Download Transparent Translucent and Opaque

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.
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. 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. 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. Notice the paths of light of the convex and
concave lenses shown below.
Convex Lense
Concave Lense