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Physics Lesson 12.3.4 - Critical Angle. Total Internal Reflection
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Welcome to our Physics lesson on Critical Angle. Total Internal Reflection, this is the fourth lesson of our suite of physics lessons covering the topic of Refraction of Light, you can find links to the other lessons within this tutorial and access additional physics learning resources below this lesson.
Critical Angle. Total Internal Reflection
When light passes from a denser medium to a less dense one, the angle of refraction is greater than the angle of incidence, as seen in the previous paragraph. If we increase the angle of incidence, the angle of refraction increases too. Therefore, it comes a moment in which the angle of refraction becomes 900 meanwhile the angle of incidence is smaller as shown in the figure.
When the refracted ray 2 is at 900 to the normal line, it does not enter in the econ medium but passes through the interface between the two media as shown in the above figure. In such a case, the corresponding incident angle is known as "critical angle". Thus, by definition, the critical angle is defined as the angle of incidence that provides an angle of refraction of 90-degrees. Make particular note that the critical angle is an angle of incidence value.
For example, for the water-air boundary, the critical angle is 48.6-degrees. This means for incidence angles smaller than 48.60, light will pass from water to air, but when the incidence angle is 48.60 the light ray emitted from inside water does not passes in air but it moves through the interface between water and air.
You have reached the end of Physics lesson 12.3.4 Critical Angle. Total Internal Reflection. There are 7 lessons in this physics tutorial covering Refraction of Light, you can access all the lessons from this tutorial below.
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Enjoy the "Critical Angle. Total Internal Reflection" physics lesson? People who liked the "Refraction of Light lesson found the following resources useful:
- Critical Angle Feedback. Helps other - Leave a rating for this critical angle (see below)
- Optics Physics tutorial: Refraction of Light. Read the Refraction of Light physics tutorial and build your physics knowledge of Optics
- Optics Revision Notes: Refraction of Light. Print the notes so you can revise the key points covered in the physics tutorial for Refraction of Light
- Optics Practice Questions: Refraction of Light. Test and improve your knowledge of Refraction of Light with example questins and answers
- Check your calculations for Optics questions with our excellent Optics calculators which contain full equations and calculations clearly displayed line by line. See the Optics Calculators by iCalculator™ below.
- Continuing learning optics - read our next physics tutorial: Interference and Diffraction of Light
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