Light Reflection on Smooth and Uneven Surfaces

Light Reflection on Smooth and Uneven Surfaces make observations and collect information about the reflective properties of surfaces of different shapes and textures (L11)

Materials:  Aluminum foil  Chrome Mylar  CDs  Flashlight  Worksheets (below and page Reproducible 5 from teacher book)

Procedure:

Preparation: Have different pairs of variables present. For instance one pair could be aluminum foil of the same size (one crumpled one not), aluminum foil of a different shape (strip versus square), bent vs. crumpled, also CDs provide an excellent material to reflect light etc.

In this exploration, students will focus on arriving at a hypothesis. The hypothesis should be in the form of a statement rather than a question. For example, “When light hits a smooth, shiny surface, it is reflected in a very orderly way.” Explain that proving a hypothesis wrong is not a failure but scientific process.

Remind students that when we are testing a hypothesis, we can change only ONE variable at a time. For instance, show students two different colours of construction paper. Keep one flat and another crumpled. Ask: what are the variables (differences) between the two objects? Have I changed only one variable?

Pass out supplies and worksheet. Observe and focus students on a solid hypothesis. Make sure they complete both sides of sheet.

Bring class back together as a group and discuss your findings of not only the exploration but also the process.

The Compact disk. The compact disk has millions of small pits etched into its back surface (this is how the data on the disk is stored) these act together to form something called a diffraction grating. This acts a bit like a mirror except the angle that the light bounces off the back surface depends on what colour it is. Therefore when different colours bounce off at different angles they separate out and you can see them individually rather then together (i.e. white). The one bright white object that may only appear to consist of three colours is a TV or monitor with a white screen. Have a look at 'True colours of a T.V.' for more detail on this.