Reflection and Refraction

Reflection and Refraction

Middle School

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Learning Objectives

• Describe the basic properties of a wave, like amplitude, wavelength, and frequency.

• Explain how light interacts with materials through absorption, reflection, and transmission.

• Analyze how a wave model of light explains things like color and brightness.

• Define refraction and explain why this phenomenon occurs.

Key Vocabulary

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Wave

A repeating disturbance that transfers energy from one place to another without transporting matter.

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Amplitude

The maximum height or distance moved by a point on a wave from its equilibrium position.

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Wavelength

The distance between two consecutive crests or troughs of a wave, determining its type.

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Reflect

To bounce light off a surface without being absorbed, allowing us to see objects.

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Refract

The bending of a light wave as it passes from one medium to another.

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Absorb

To take in light energy rather than reflecting it, often converting it into heat.

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Properties of a Wave

• A wave is a repeating disturbance that transfers energy from one place to another.

• Wavelength is the distance from one peak of the wave to the next peak.

• Frequency is how many complete waves pass a certain point every single second.

• Amplitude is the wave's height from its rest position and relates to brightness.

Multiple Choice

What property of a wave is defined as the distance between two consecutive peaks?

• Amplitude

• Wavelength

• Frequency

• Energy

Light's Interaction with Materials

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Reflection

• Light bounces off the surface of an object like a mirror.

• We see objects because they reflect light into our eyes.

• A surface's smoothness affects how the light is reflected.

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Absorption

• Light energy is taken in by a material, not reflected back.

• This absorbed energy is often converted into heat or thermal energy.

• Dark-colored objects get warmer in the sun because of this.

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Transmission

• This occurs when light passes through a material like clear glass.

• Materials that let light pass through are described as transparent.

• The light can bend, or refract, as it passes through.

Multiple Choice

A clear glass window allows light to pass through it. Which interaction of light is this an example of?

• Absorption

• Reflection

• Transmission

• Refraction

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What Is Refraction?

• Light bends, or refracts, when it moves from one material to another.

• A straw in a glass of water looks bent because of this effect.

• This bending happens because light changes its speed in different materials.

• Lenses use refraction to focus light and form clear images in cameras.

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Multiple Choice

What is the primary cause of light refraction?

• A change in the color of the light.

• A change in the speed of light as it enters a new medium.

• The light bouncing off the surface of a new medium.

• The light being absorbed by the new medium.

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Color and Light Absorption

• An object's color is the specific wavelength of light it reflects.

• White objects appear white because they reflect all colors of light.

• Black objects appear black because they absorb all colors of light.

• Absorbed light energy converts to heat, making black objects feel warmer.

Multiple Choice

Why does a blue shirt appear blue?

• It absorbs blue light.

• It reflects all colors of light.

• It reflects blue light and absorbs other colors.

• It transmits blue light.

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Common Misconceptions

Misconception	Correction
Our eyes emit light beams, which is how we see.	We see because light from a source reflects off objects and enters our eyes.
A black object has a black pigment or color.	Black is the absence of reflected light. A black object absorbs all wavelengths of visible light.
Light can only travel in a straight line and cannot bend.	Light always travels in a straight line within a single medium, but it bends (refracts) when it passes from one medium to another.

Multiple Choice

Why does a dark-colored car get hotter in the sun than a light-colored car?

• The dark color reflects more light, generating heat.

• The dark color absorbs more light energy, which is converted into heat.

• The light-colored car transmits light, keeping it cool.

• The material of the dark car is a better conductor of heat.

Multiple Choice

If Wave A has a higher frequency than Wave B, what does this imply?

• Wave A has a longer wavelength than Wave B.

• Wave A carries less energy than Wave B.

• More waves of A pass a point in one second than waves of B.

• Wave A has a greater amplitude than Wave B.

Multiple Choice

A pencil in a glass of water appears broken at the water's surface. What is the best explanation for this phenomenon?

• The water magnifies the pencil, making it look larger.

• Light from the pencil reflects off the water's surface.

• Light from the pencil refracts as it passes from the water to the air, changing its apparent position.

• The glass absorbs the light from the pencil, causing a distortion.

Multiple Choice

How do eyeglasses help a person with blurry vision see clearly?

• They filter out harmful colors of light.

• They reflect excess light away from the eye.

• They absorb light to reduce brightness.

• They use shaped lenses to refract light and focus it correctly on the retina.

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Summary

• Light is a form of energy that travels in waves.

• Light is reflected, absorbed, or transmitted when it strikes an object.

• Reflected light allows us to see objects and their specific colors.

• Absorbed light becomes heat, and refracted light bends between mediums.

Poll

On a scale of 1-4, how confident are you about the concepts of reflection and refraction?

• 1

• 2

• 3

• 4