Changes Caused by Light

Changes Caused by Light

Middle School

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Learning Objectives

• Describe the basic properties of waves, including wavelength, amplitude, and frequency.

• Explain that light is a wave that carries energy and can be reflected or absorbed.

• Use a model to describe how light's interaction with materials causes heating.

• Relate a light wave's amplitude and frequency to the energy it transfers.

Key Vocabulary

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Wave

A repeating pattern that moves energy from one place to another without transferring any matter.

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Wavelength

The distance between two identical points on a wave, like from one peak to the next.

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Amplitude

The maximum height or depth of a wave from its rest position, which indicates its energy.

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Frequency

The number of complete waves that pass by a specific point in a given amount of time.

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Transmit

To allow energy, such as light, to pass through a material from one side to the other.

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Reflect

To bounce energy, like light or sound, off of the surface of an object or material.

Key Vocabulary

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Absorb

To take in energy from light and convert it into another form, like heat.

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Light Source

An object or entity that produces and emits its own special kind of light energy.

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Emit

To release or send out energy from a source in the form of waves or particles.

What Are the Properties of a Wave?

• Wavelength is the distance between two consecutive peaks of a wave.

• Amplitude is the maximum height of a wave from its central resting position.

• Frequency is the number of waves that pass a point per second.

Multiple Choice

What does the wavelength of a wave measure?

• The distance between two consecutive peaks of a wave.

• The maximum height of a wave from its resting position.

• The number of waves that pass a point per second.

• The speed at which the wave is traveling.

Multiple Choice

Which property of a wave describes its maximum height from its central resting position?

• Wavelength

• Frequency

• Amplitude

• Speed

Multiple Choice

If an observer notices that more waves pass by a certain point every second, what can be concluded?

• Its frequency has increased.

• Its wavelength has gotten longer.

• Its amplitude has decreased.

• Its frequency has decreased.

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Light: A Wave Carrying Energy

• Light is an electromagnetic wave that can travel through the vacuum of space.

• A light wave's amplitude determines its brightness; higher amplitude means more energy.

• A light wave's frequency determines its perceived color, like red or violet.

• Higher frequency light carries more energy than lower frequency light.

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Multiple Choice

What is light?

• An electromagnetic wave that carries energy.

• A type of sound wave that requires a medium.

• A form of matter that has a fixed shape.

• A particle that has mass but no energy.

Multiple Choice

What is the relationship between a light wave's properties and what we observe?

• The amplitude of the light wave determines its brightness.

• The frequency of the light wave determines its speed.

• The color of the light wave determines its direction.

• The energy of the light wave determines its medium.

Multiple Choice

Assuming two light waves have the same amplitude, which one would carry the most energy?

• A high-frequency violet light wave.

• A low-frequency red light wave.

• A light wave traveling through a vacuum.

• A light wave with a very low amplitude.

How Light Interacts with Objects

• Reflection is when light bounces off an object, like a mirror.

• Absorption is when light is taken in by an object, creating heat.

• Transmission is when light passes through an object, like glass or water.

Multiple Choice

What is it called when light bounces off an object, like a mirror?

• Reflection

• Absorption

• Transmission

• Refraction

Multiple Choice

Why does a dark-colored t-shirt feel warmer in the sun than a light-colored one?

• The light is absorbed by the shirt, which creates heat.

• The light reflects off the shirt, which cools it down.

• The light passes through the shirt, which traps air.

• The light is transmitted through the shirt, which warms the skin.

Multiple Choice

A car with clear glass windows is parked in the sun. Which statement best explains why the inside of the car gets hot?

• Light is transmitted through the glass and then absorbed by the car's interior, creating heat.

• Light is reflected by the glass, which heats up the air inside the car.

• Light is absorbed by the glass, which transfers heat into the car.

• Light is reflected by the car's interior and is trapped by the glass.

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Common Misconceptions

Misconception	Correction
We see because our eyes emit light.	We see because our eyes detect light reflected off objects.
Color is a physical property of an object.	An object's color depends on the wavelengths of light it reflects.
A clear window lets all light pass through.	Transparent materials also reflect and absorb a small amount of light.
All light is visible to humans.	Visible light is a small part of the electromagnetic spectrum.

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Summary

• The wave model explains light as energy traveling in waves.

• Unlike sound, light can travel through the vacuum of space.

• Light is reflected, absorbed, or transmitted when it hits a material.

• The absorption of light energy can cause materials to heat up.

Poll

On a scale of 1-4, how confident are you about explaining how light interacts with different materials?

• 1 (Not Confident)

• 2 (A Little Confident)

• 3 (Mostly Confident)

• 4 (Very Confident)