Total Internal Reflection Application of Total Internal Reflection

Total Internal Reflection

Application of Total Internal Reflection ¡ Diamonds ¡ Fibre optics ¡ Triangular prism

Total Internal Reflection - - When light travels from more dense material to less dense material the amount of reflection can be greater than the amount of refraction As the angle of incidence increases, the angle of refraction will always be greater than the angle of incidence The angle at which the incident ray causes the refractive ray to disappear is called the critical angle At the critical angle and above, all the incident light will be reflected back into the denser medium, this is called total internal reflection Total internal reflection occurs when these two conditions are met: 1. Light travelling from more dense material to less dense material 2. Angle of incidence is at or greater than the critical angle Refraction Demonstration

Total Internal Reflection • Green ray – angle of incidence is less than critical angle, therefore ray is refracted in 2 nd medium • Red ray – angle of incidence is equal to critical angle, therefore angle of refraction is 90 o • Blue ray – angle of incidence is greater than critical angle, therefore total internal reflection is observed

Critical Angle

Diamonds Are Forever ¡ ¡ One of the features that make diamonds so attractive is the fact that they sparkle This “sparkling” is due to the cut of the diamond faces, which results in the total internal reflection of light

Fibre Optics ¡ ¡ ¡ An optical fibre is made of a tiny glass fibre called the core that is about the size of a human hair A cladding (protective coating) made of a different type of glass covers the core The speed of light in the cladding is higher than it is in the core, thus light is totally internally reflected and will travel down the core

Total Internal Reflection Video