How light travels, shadows and transparent materials

Home learning focus

In this lesson, you will learn about how light travels, shadows and transparent materials.

This lesson includes:

  • three videos demonstrating how light travels.
  • two activities to enhance learning about how light travels and shadows.
Supermovers look at Light

How light travels

Light travels in straight lines.

If an object is transparent it means you can see the object clearly and light can completely pass through it.

Some objects let some light through, but not enough to allow us to see objects clearly.

We call these materials translucent or semi-transparent.

Objects which let no light through are called opaque.

Blue translucent vases

Did you know?

A frog has been discovered in Costa Rica, whose skin in translucent you can see all its organs in its body.

They named it the glass frog...watch the clip below to learn more.

Glass Frog discovered in Costa Rica

Shadows

What happens when an opaque object is placed in front of a light source?

When an opaque object is placed in front of a light source, it prevents the light from passing through.

This then creates a dark area or shape on a surface as a result.

This is called a shadow.

Changing shadows

By moving the position of the light source, we change the size of the shadow.

  • The closer to the light source an object is, the bigger the shadow will be. This is because the object blocks more of the light.

  • The further away from the light source an object is, the smaller the shadow will be. This is because the object blocks less of the light.

  • When the light source moves directly above an object, the shadow will be directly below the object.

  • When the light source is to one side of the object, the shadow will appear on the opposite side and the shadow will be longer.

Key facts to remember:

  • Light can travel through transparent objects.

  • Shadows are formed when light is blocked.

  • Shadows can be formed from natural and artificial light.

  • We can change the size of the shadow by moving the object further away or closer from the light source.

How light travels in straight lines

Practise

There are lots of fun ways to try out your science skills.

Activity 1

Investigation

Experiment with different objects around your house to create shadows.

  • Which object makes the smallest shadow?
  • Which object makes the biggest shadow?

You might want to:

  • Experiment with different light sources.
  • Experiment with transparency of different objects.

You could also make a list of all the transparent objects and translucent objects you can find around your house.

Activity 2

Light worksheet

Have a go at applying your knowledge of how light travels with this worksheet from Twinkl

Light and Shadow worksheet

There's more to learn

Have a look at these other resources around the BBC and the web.

More lessons for Year 7 and S1
KS3 Physics
KS3 Physics
Supermovers