The Critical Angle
The Critical Angle Video Tutorial explains what a critical angle is and why it is important to understanding total internal reflection. The formula for critical angle is derived from Snell's Law. It use in calculating the critical angle for three different boundaries is demonstrated.
The video lesson answers the following questions:
- What is the critical angle?
- How do you calculate the critical angle value?
Video
You can watch the video below, or click here to watch on YouTube (opens in a new tab).
To improve the effectiveness of the learning experience, The Physics Classroom has provided the following tools:
Additional and Related Learning Tools
The Calculator Pad, Refraction and Lenses Chapter, Problem Sets 10 - 12
If you need practice solving Physics word problems, you're going to have difficulty finding a better tool than our Calculator Pad. You will have problems of varying difficulty, immediate feedback, multiple opportunities for correction, and a collection of help tools to guide you through to the solution. These sets include critical angle calculations.
Minds On Physics, Refraction and Lenses Module, Mission RL6
Student persistence with Minds On Physics combined with reflective thinking and the use of our Help function will put any student at the top of the class. This mission pertains to total internal reflection and the critical angle. It's a perfect follow-up activity.
Physics Interactive, Refraction and Lenses Chapter, Refraction Simulation
Sometimes you learn best by playing. And our simulations allow you to do just that. Our Refraction simulation allows you to explore the variables that impact the amount of light energy that reflects and the amount that refracts. Explore TIR using our simulation and then follow it up with a Concept Checker on the same topic
Concept Builders, Reflection and Refraction Chapter: Total Internal Reflection
Concept Builders will help do what it's name boasts of - build a concept. This Concept Builder will test your understanding of the requirements for total internal reflection. The activity targets concepts from this video and the previous one on Total Internal Reflection.
The Physics Classroom Tutorial, Refraction and the Ray Model of Light, Lesson 3, The Critical Angle
Our written tutorial pages form the basis of most videos. So when you need a quick reference, the Tutorial page is a great place to start. This page provides complete coverage of the of the video.
Teacher Resources
Curriculum Corner, Refraction and Lenses
Our Curriculum Corner section of the website includes a large collection of Think Sheets that make great complements to the video. Each Think Sheet focuses on a single concept and is structured to incrementally guide a student through the concept. They make for great follow-ups to the video, good cooperative group activities, and inclusions in any lesson plan. And if you need source documents (Microsoft Words), extended licensing rights, and solutions, consider the purchase of our low-cost Solutions Guide download. Here's a Think Sheet that fits the video quite well:
Total Internal Reflection
The Calculator Pad, Refraction and Lenses Chapter, Problem Sets 10 - 12
If you need practice solving Physics word problems, you're going to have difficulty finding a better tool than our Calculator Pad. You will have problems of varying difficulty, immediate feedback, multiple opportunities for correction, and a collection of help tools to guide you through to the solution. These sets include critical angle calculations. Try it with a Task Tracker account and you can customize the problem sets, combine them into one shorter problem set, and view progress reports on your students.
Minds On Physics, Refraction and Lenses Module, Mission RL6
Student persistence with Minds On Physics combined with reflective thinking (no pun intended) and the use of our Help function will put any student at the top of the class. This mission pertains to total internal reflection and the critical angle. It's a perfect follow-up activity. It can be effectively done with or without a Task Tracker account.
Physics Interactives, Refraction and Lenses Section, Refraction
Our refraction simulation provides a great environment for students to explore what happens when light reaches the boundary between two materials. Combine the simulation with the use of one of our student activity sheets (we have an exceptional one on TIR) and the accompanying Concept Checker and you will have the start of a great lesson plan.
Concept Builders, Reflection and Refraction Chapter: Total Internal Reflection
Concept Builders will help do what it's name boasts of - build a concept. This Concept Builder will test your understanding of the requirements for total internal reflection. Do it now or do it after you've watched this video and the next on the Critical Angle.
Minds On Physics, Refraction and Lenses Module, Mission RL5
Student persistence with Minds On Physics combined with reflective thinking and the use of our Help function will put any student at the top of the class. This mission pertains to total internal reflection. Mission RL6 (above) may be a better fit to this video.
The Physics Classroom Tutorial, Refraction and the Ray Model of Light, Lesson 3, The Critical Angle
Our written tutorial pages form the basis of most videos. So when you need a quick reference, the Tutorial page is a great place to start. This page provides complete coverage of the of the video.
Lesson Notes
Download (opens in a new tab) or view below
Slides
Do you like the slides we used? They are available in our low cost Teacher Presentation Pack, along with other updated materials used in our presentation.