https://phet.colorado.edu/en/simulations/bending-light
Lab Overview
Refraction
In this lab, students explore the concept of refraction, examining how light bends as it passes through different media. Using the PhET Bending Light simulation, students can manipulate light rays and observe changes in angle and speed as light moves between substances like air, water, and glass. This interactive lab provides an engaging way for students to understand how refraction is part of everyday phenomena, from lenses to prisms.
Learning Objectives
Aligned with the Victorian Curriculum, students will:
- VCSSU130: Describe how light can be reflected, refracted, and absorbed.
- VCSSU131: Apply the principles of light behavior to explain real-world phenomena.
By the end of this lab, students should be able to:
- Define refraction and explain why light bends when it passes through different media.
- Describe the relationship between the angle of incidence and the angle of refraction.
- Apply Snell’s Law to calculate refractive indices and angles in simple scenarios.
ACARA Digital Literacy Capabilities
- Communicate: Expressing experimental results using digital presentations.
- Select and operate tools: Students engage with simulations that demonstrate refraction phenomena.
Lab Instructions
- Access the Simulation: PhET Bending Light Simulation.
- Basic Refraction Exploration:
- Direct a light ray through the boundary between air and water, observing how the angle changes.
- Note the difference in the speed of light between the two media and how this affects refraction.
- Measure Angles:
- Use the protractor tool in the simulation to measure the angle of incidence and the angle of refraction.
- Record measurements as light passes from air into glass, then from glass to water, noting the variation in bending.
- Apply Snell’s Law:
- With the provided values, use Snell’s Law (n₁sinθ₁ = n₂sinθ₂) to calculate unknown angles or refractive indices for different materials.
Assessment Questions
- What is refraction, and why does light bend when it enters a new medium?
- Describe what happens to the angle of a light ray as it passes from a less dense to a more dense medium (e.g., air to glass).
- Using Snell’s Law, calculate the angle of refraction when light passes from air (n=1.0) to water (n=1.33) at an angle of incidence of 30°.
- Explain a real-life application of refraction, such as its role in lenses or corrective eyewear.
Teacher Notes
Integrating with Lessons:
- This lab is ideal for units on light behavior, complementing lessons on reflection and transmission.
- Encourage students to observe refraction in everyday objects, like a straw in a glass of water, to reinforce concepts visually.
Common Misconceptions:
- Students may think light always bends the same way; emphasize that the direction and degree depend on the properties of each medium.
- Clarify that light changes speed, not frequency, as it moves through different media, which causes the bending.
Extension Activities:
- Challenge students to explore total internal reflection by directing a light ray at different angles and observing critical angles.
- Have students investigate the effect of different refractive indices by experimenting with various media, linking it to material properties and real-world applications.
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