Engineering Water Prisms

In this lesson, students explore how light energy can be reflected, refracted, or absorbed when it interacts with matter. They then apply this knowledge to design a device that uses water and mirrors to create rainbows that shine on a vertical surface.

• Both sound and light are forms of kinetic energy that can be transferred from one place to another.
• Sound moves in waves of vibrating molecules. It begins at a source and travels outwards until the energy is fully passed on.
• Light travels in a straight line until it comes into contact with matter, at which point it can be absorbed, reflected, or refracted.
• Light can also be understood as a wave, similar to a sound wave. Light waves come in many sizes.

• How does sound move from one place to another?
• How is light similar to sound? How is light different from sound?
• How does the path of light change when it is reflected?
• What would happen to our ability to see if light couldn’t reflect off of objects?
• How does the path of light change when it is refracted? How does the path of light change when it is absorbed?
• How are transparent materials different from translucent materials?
• Why can’t people see all of the light waves that exist?
• How do light waves explain why we see different colors?
• How do prisms support the argument that white light is made up of a mixture of different colors?
• Why are rainbows a result of reflection, refraction, and dispersion?

Dispersion : the separation of visible light into its different colors

Light : a form of kinetic energy that travels through space

Rainbow :  an arc made up of different colors that forms in the sky when light is reflected, refracted, and dispersed in water droplets

Gravity :  a force of attraction between all matter

Reflection :  occurs when light bounces off of the surface of an object

Refraction : occurs when a ray of light passes from one medium to another but changes direction

White Light :  a mixture of all the colors that make up visible light: red, orange, yellow, green, blue, indigo, and violet

Can You Fly Over a Rainbow?

In 2014, Melissa Rensen was on a plane. She took a photograph out the window. Later, Melissa looked at her pictures. She saw bands of colors just below the clouds. It looked like the plane was flying over a rainbow.

Many websites linked to her photo. They wrote articles about it.

However, people began to question the photograph. They said it isn’t possible to fly over a rainbow. This is because rainbows are optical illusions. It is impossible to see a rainbow in front of you and to fly over it.

Rainbows are Light

Rainbows are caused by light interacting with matter. All light is a form of kinetic energy that travels through space. The sun is the largest source of light on Earth.

Light is complex. There is still much that scientists don’t know about it. Scientists use different models to better understand how light moves and how it interacts with matter.

One model is a ray model. This model describes how light moves in a straight line. These straight-line paths are called light rays. When you see a narrow beam of light, it is actually a bundle of many light rays. The light rays are parallel. They move in the same direction as each other.

Another model is a wave model. This is because in many instances, light behaves in a similar way to sound waves and other kinds of waves. However, unlike sound waves, light doesn’t need to travel through matter. We’ll use both models to describe how light interacts with matter to form rainbows.

For the hands-on activity, students investigate how light interacts with different materials and then apply what they know about light energy to engineer a device that uses specific materials to create rainbows. This lesson has two parts, an investigation and an engineering challenge. In the investigation, students investigate how light interacts with different materials. In the engineering challenge, students use information from a scenario to define the main problem facing a museum that needs to project a certain spectrum of light on a statue. Students work in teams to come up with possible solutions to solve the problem.