How Do Shadows Change? WALT: find patterns when investigating how shadows change size.
WILF: - Explain how a shadow is formed. - Understand the role light-position plays in casting a shadow. - See that shadows can become smaller or bigger depending on the object.
Light can only travel in a straight line. A shadow is formed when something blocks light. Here is a shadow puppet show of Little Red Riding Hood. The shadows are formed when light is shone on the puppets. The puppets block the light and a shadow is formed.
What do you notice about the shape of the puppet and the shape of the shadow? Have you ever noticed…
When you are sitting near a tree on a sunny day and time passes, you find that you have to keep moving to stay in the sun. This is because the tree is blocking the light from the sun and casting a shadow onto the grass. The position of the sun in the sky causes the shadow to be cast in different directions. The reason that a shadow has been cast by the tree is that the light does not pass through it. Solid objects block light and a shadow will be cast on the opposite side of an object where the sun is not shining.
The sun is behind the tree (light source).
The tree is the solid object blocking the light.
The shadow is cast onto the ground on the opposite side to where the sun is. Looking at the two pictures below and using your understanding from the previous slides. Can you tell what the position of the sun would be in to cast a shadow on these objects? How shadows can change.
The size of a shadow can also change depending on the position of the object. Look at the shadow the ball makes.
What do you think will happen if the ball is moved closer to the torch? What will happen if the ball is moved further away from the torch? The closer to the light source Were your an object is, the bigger the predictions shadow will be. This is because correct? 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, the shadow will change
When the light source is directly above the object, the shadow will be directly underneath. When the light source is to one side of the object, the shadow will appear on the opposite side. The shadow will also be longer. Your task: Create a shadow puppet of your choice. Take photos or record a video of what happens when you move the puppet closer to the light and further away from it. You could also show what happens when the position of the light source moves.
The link below will explain how you can make your own shadow puppet. http://www.planet-science.com/categories/under-11s/our- world/2012/04/make-your-own-shadow-puppets.aspx