The Arizona STEM Acceleration Project

The Polarization of Light

The Polarization

of Light

An 11th and 12th Grade STEM Lesson

Donna Brunjes

March 2024

Notes for Teachers

• Context: This lesson takes place first in a classroom then in a lab for two consecutive days for approximately one hour per day.
• Students work in small groups of 2-4 students each.
• This lesson introduces the topic of light polarization.
• Students should have prior basic knowledge of the electromagnetic spectrum, properties of transverse waves (light waves), and how light waves oscillate and propagate.
• Teacher explains applications of light polarization in modern devices and technology.

List of Materials:

• Introductory lesson/assignment on what light polarization is
• Examples of how polarized light is the interaction between electromagnetic (transverse) waves and matter
• Examples of how polarized light is used in modern devices and technology
• Laser pointers and white light flashlights
• Plastic hair combs
• Diffraction gratings
• Prism eyeglasses, 3D glasses and polarized sunglasses
• Colored filter papers
• Polarizing filters and clear plastic sheets
• Polarizing cellophane tape
• Team Lab Data Collection and Question Sheet

Arizona Standards

Science Standards:

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HS.P2U1.5: Construct an explanation for a field’s strength and influence on an object (electric, gravitational, magnetic).

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HS.P4U1.10: Construct an explanation about the relationships among the frequency, wavelength, and speed of waves traveling in various media, and their applications to modern technology.

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Science and Engineering Practices for High School:

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• Analyzing and Interpreting Data
• Using Mathematics and Computational Thinking
• Planning and Carrying Out Investigations
• Obtaining, Evaluating, and Communicating Information
• Constructing Explanations and Designing Solutions
• Engaging in Argument from Evidence
• Asking Questions and Defining Problems

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Objective(s):

Today we review how light is both a wave and a particle. Next, we will explore how light can be polarized so that light waves can propagate in a certain direction and be restricted to a particular plane (horizontal or vertical) as a result of their interactions with certain materials or structures.

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Objective(s) (continued):

Then we will learn about how filters are commonly used to polarize light. Polarizing filters selectively absorb (block) or transmit certain light waves due the polarization properties built-in each filter. The filters depicted below, for example, are called circular polarizers and are used in photography and optical systems.

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Objective(s) (continued):

We will learn about devices such as sunglasses which are polarized to block out 30-50% of sunlight waves to reduce glare, enhance vision, and protect against harmful UV radiation. Other technologies use similar polarization techniques via filters to selectively absorb or transmit light waves. Polarized filters are aligned either horizontally or vertically to block waves oscillating in the corresponding direction.

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Objective(s) (continued):

Tomorrow we will explore through hands-on activities first how light is both a wave and a particle. We will then explore how light waves can be examined by looking at their constituent colors, wavelengths, intensities and interference patterns. Next we will observe how different filters and optical lenses in eyeglasses can polarize light and learn about the benefits of viewing images through polarization.

We will then observe how colored filter papers can also polarize lights. Finally, we will create polarized artwork which demonstrates how we can selectively absorb and transmit light along horizontal and vertical plane orientations.

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Agenda (lesson time)

During the Lesson (60 minutes):

Understanding how light is both a wave and a particle (wave particle duality theory) and part of the electromagnetic spectrum

What is light polarization?

Why do we want to polarize light?

How do filters and optical lenses work to polarize light?

How is polarized light used in modern devices and technology?

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During the Lab (60 minutes):

How do waves move?

What are the different properties of light waves?

How do filters or lenses with different light polarization capabilities enable us to see images?

How does the alignment of a polarizing axis influence the horizontal or vertical absorption or transmission of light waves?

Intro/Driving Question/Opening

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• What do we mean by the “polarization of light?”
• Why do we want to selectively absorb (block) or transmit some types of light?
• How do the unique properties of light waves enable us to “adjust” light wave absorption or transmission?
• What is the difference between a light wave oscillating vs. a light wave propagating?
• Did you know that light waves can have different orientations but polarized light waves will have specific horizontal and vertical orientations?
• Did you know that light polarization is used in LCD displays on TVs and smartphones, photography lenses and sunglasses?
• Did you know that light polarization is also used in fiber optic and internet cables, in eye vision testing equipment and in medical imaging?
• What other technologies might benefit from light polarization which typically reduces glare, enhances image contrast and clarity, and improves color saturation?

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Lesson Instructions

During Lesson:

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• Teacher introduces light polarization and explains how polarized light is the interaction between electromagnetic waves (transverse waves) and matter
• Teacher provides examples of how polarized light is used in modern devices and technologies
• Teacher asks students driving questions about light waves, how they move (their particles and their waves), how they can be polarized and how polarized light is currently used
• Students complete an introductory lesson/assignment with multiple choice, matching, true-false and short answer questions and turn in their assignments for teacher review and grading

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Hands-on Activity Lab Instructions

During Lab:

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• Students working in teams of 2-4 students visit different lab stations already set up with light-related activities
• Students take notes at each station on their “Team Lab Data Collection and Question Sheet” and answer questions

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Lab Station Activities include:

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• Recreation of Young’s Double Slit Experiment using red laser pointers and plastic combs
• Using diffraction gratings with white light to demonstrate the electromagnetic spectrum, and with colored laser pointers to disperse light into its constituent colors, wavelengths, and intensities
• Observing images and light patterns on paper using white light and colored laser pointers with prism eyeglasses, 3D glasses and polarized sunglasses
• Blocking or transmitting light through the use of colored laser pointers and colored filter papers
• Creating polarized artwork (for students to keep) using clear plastic sheets, polarized filters and polarized cellophane tape

Team Lab Data Collection and Question Sheet includes:

• Data collected from students’ hands-on activities
• Responses to questions on properties of light waves and light polarization
• Knowledge of technologies using light polarization and suggested possible future applications

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Assessment

Students complete two (2) assessments while working together in groups of 2-4 students. These assessments are to be submitted for teacher review and grading:

Formative Assessment:

• Introductory lesson/assignment with multiple choice, matching, true-false and short answer questions

Summative Assessment:

• “Team Lab Data Collection and Question Sheet” which includes: 1) students’ analysis and interpretation of data they collected from their hands-on activities, 2) students’ responses explaining properties of light waves and light polarization, and 3) students’ knowledge of technologies using light polarization and suggested possible future applications

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Differentiation

Students who need further remediation during the lesson or lab component, specifically with understanding the properties of electromagnetic waves, will be given a remedial assignment that reviews different aspects of these waves. Students would be asked to label and explain the different components of these waves as follows:

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Remediation

Extension/Enrichment

For further enrichment, students may which to further explore some of the technologies that utilize light polarization. Once such application is LCD displays on televisions.

Students would be given a research assignment to (1) define key terms such as “backlight,” “liquid crystal panel,” “polarizing filters,” “pixel control,” “color filters” and “image formation” and, (2) write a one-page essay using these terms to explain how LCD televisions use light polarization to produce high quality images with sharp details and vibrant colors.

Another enrichment activity might be to have students create their own customized polarized lens glasses making their own cardboard frames and using the colored filtered paper available from the lab component of the lesson. This is based on the key principle that polarized glasses selectively filter out specific orientations of light waves.

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