Behavior of Light

Behavior of Light

Middle School

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Learning Objectives

• Define and compare the key properties of light: reflection, refraction, and scattering.

• Explain the composition of white light and the relationship between color and wavelength.

• Describe how light absorption and reflection determine the color of an object.

• Identify the primary colors of light and the secondary colors they create when mixed.

• Understand light polarization and how special filters can affect the light waves.

Key Vocabulary

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Reflection

The bouncing back of light when it strikes a surface that does not absorb its energy.

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Refraction

The bending of a light wave as it passes from one medium to another, like air to water.

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Scattering

The process by which light spreads in all directions when it collides with particles of matter.

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Visible Spectrum

The band of colors (ROYGBIV) that is produced when white light is separated into its component wavelengths.

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Wavelength

The distance between corresponding points of successive waves, which determines the color and energy of light.

Properties of Light

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Reflection

• Reflection is when light bounces off an object's surface.

• Smooth surfaces like mirrors reflect light at the same angle.

• This is why you can see your own clear image.

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Refraction

• Refraction is the bending of light as it changes speed.

• It happens when light passes from one medium to another.

• This is why a pencil in a glass of water looks bent.

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Scattering

• Scattering occurs when light rays bounce off in all directions.

• This happens when light hits rough surfaces or tiny particles.

• The scattering of sunlight makes our sky appear blue.

Multiple Choice

What is the term for the bending of light as it passes from the air into a different medium like water?

• Reflection

• Refraction

• Scattering

• Absorption

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The Visible Spectrum

• White light is a mixture of all the colors we can see.

• These colors are red, orange, yellow, green, blue, indigo, and violet (ROYGBIV).

• Red light has the longest wavelength; violet light has the shortest.

• A prism separates white light by bending each wavelength by a different amount.

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Multiple Choice

Which color of light in the visible spectrum has the longest wavelength?

• Violet

• Green

• Red

• Blue

How We See Color

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Colored Objects

• An object's color depends on the light wavelengths it reflects.

• Most objects absorb some wavelengths of light and reflect others.

• A red flower looks red because it reflects red light.

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White Objects

• White objects appear white by reflecting all wavelengths of light.

• They do not absorb any of the visible colors of light.

• All light shining on them reflects back to our eyes.

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Black Objects

• Black objects appear black by absorbing all wavelengths of light.

• They do not reflect any of the visible colors of light.

• No light is reflected from the object to our eyes.

Multiple Choice

Why does a green leaf appear green to our eyes?

• It absorbs green light and reflects all other colors.

• It reflects green light and absorbs all other colors.

• It absorbs all light, but our brain sees it as green.

• It reflects all colors of light equally.

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Light and Transparent Objects

Transmitted Light

• Transparent objects, like colored glass, have the color of the light that they transmit.

• The glass absorbs all other colors of light that try to pass through it.

• For example, green glass only allows green light to pass through to your eyes.

Objects in Filtered Light

• An object's appearance can change when it is viewed under a colored or filtered light.

• Under red light, a red or a white object will appear red to your eyes.

• A blue object looks black because there is no blue light for it to reflect.

Multiple Choice

What color would a blue book appear if you looked at it under a red light?

• Blue

• Red

• White

• Black

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Primary and Secondary Colors of Light

• The primary colors of light are Red, Green, and Blue (RGB).

• Mixing these three primary colors in equal amounts results in white light.

• Secondary colors are formed by mixing two primary colors of light together.

• These are Yellow (Red + Green), Magenta (Red + Blue), and Cyan (Green + Blue).

Multiple Choice

Which of the following are the three primary colors of light?

• Red, Yellow, Blue

• Red, Green, Blue

• Cyan, Magenta, Yellow

• Red, Orange, Yellow

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What Is the Polarization of Light?

• Light from the sun is unpolarized, with waves vibrating in all directions.

• Polarization is a process that makes light waves vibrate in only one direction.

• A polarizing filter acts like a gate, letting specific light waves pass through.

• Using two filters at different angles can block the light from passing through.

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Multiple Choice

What is the most common way to transform unpolarized light into polarized light?

• Using a mirror

• Using a lens

• Using a filter

• Using a prism

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Common Misconceptions About Light

Misconception	Correction
An object's color is inside the object itself.	The color we see is the light that an object reflects.
The sky is blue because it reflects the ocean.	The sky is blue because the atmosphere scatters blue light.
All light is visible to the human eye.	Visible light is a small part of the electromagnetic spectrum.

Multiple Choice

How is refraction different from reflection?

• Refraction is bouncing, while reflection is bending.

• Reflection is the bouncing of light off a surface, while refraction is the bending of light as it passes through a new medium.

• Reflection only happens with mirrors, while refraction only happens with water.

• They are the same process.

Multiple Choice

Why does a black car get hotter in the sun than a white car?

• The black car reflects more light energy.

• The white car absorbs more light energy, converting it to heat.

• The black car absorbs more light energy, converting it to heat.

• Color has no effect on how much heat is absorbed.

Multiple Choice

A banana reflects yellow light. What color would a banana appear to be if you viewed it under a pure blue light?

• Yellow

• Green

• Blue

• Black

Multiple Choice

A 3D movie works by sending a different image to each eye using polarized lenses. How do two polarizing filters, one for the screen and one for your glasses, make this possible?

• They bend the light in different directions for each eye.

• They filter the light so only certain orientations can pass through, blocking the incorrect image from each eye.

• They change the color of the light for each eye.

• They make the light brighter for one eye and darker for the other.

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Summary

• Light can reflect (bounce), refract (bend), or scatter (spread out).

• White light is a mix of all colors, each with a different wavelength.

• An object’s color is the light it reflects; it absorbs all other colors.

• White objects reflect all colors, while black objects absorb all of them.

Poll

On a scale of 1-4, how confident are you about the concepts covered in today's review?

• 1 (Not confident)

• 2 (A little confident)

• 3 (Mostly confident)

• 4 (Very confident)