Light and shadows

Light and shadows

Learning objectives

To show what already know about topic of light 

To understand that shadows form when light is blocked 

To understand that the shape of a shadow depends on the object that it is a shadow of 

Name as many sources of light as you can

What is a shadow?

www.bbc.co.uk

Key terms

Objects can be classified as:

Opaque - objects block all light.

Translucent - objects partially block light.

Transparent - objects allow light through.

Shadows

A shadow forms when an opaque or non-transparent object blocks light from passing through and reaching a surface on the other side.

Shadows do not have any details – they are simply a silhouette.

Shape and size of shadows

The shape of a shadow depends on the shape of the object blocking the light source.The size of a shadow depends on the distance between the light and the object. The larger the distance, the smaller the shadow.

Size of the shadow

Because light travels in straight lines the shape of the shadow will be the same as the outline shape of the object.

 The size of the shadow is larger when the light source and object move closer to each other as more of the light is blocked.

Shadow size

The larger the distance between the object and the light, the smaller the shadow.

The smaller the distance, the larger the shadow. 

The distance between the object and light affects shadow size.

Absolutely agree, it's a crucial factor.

Disagree, shape matters more than distance.

Neutral, both distance and shape are important.

Only partially agree, light intensity plays role.

Opaque objects are essential for shadow formation.

Absolutely agree, they block all light.

Disagree, translucent objects can also help.

Neutral, shadows exist with various objects.

Only partially agree, need light source too.

What is true about shadow details?

1. Shadows are 3D
2. Shadows do not have details
3. Shadows vary in detail
4. Shadows show color

How does distance affect shadow size?

1. Distance has no effect
2. Closer objects create smaller shadows
3. Closer objects create larger shadows
4. Larger distance creates larger shadows

What forms a shadow?

1. A translucent object
2. A light bulb
3. An opaque object blocks light
4. A transparent object

What type of object blocks all light?

1. Shadows
2. Transparent objects
3. Opaque objects
4. Translucent objects

Activity

Draw lines to match the shadows on the left with the correct pictures on the right

Activity

Place an object on a piece of plain paper. Shine a torch onto the object from a distance. 

Draw around the shadow of the object. Then move the torch closer and draw around the shadow again. 

What has happened to the shadow as the light got closer?