SNC2D Physics: Topic 12 Total Internal Reflection PDF

SNC2D – PHYSICS LIGHT & GEOMETRIC OPTICS 12.5 Total Internal Reflection  Total Internal Reflection RECALL  If light enters a second medium at an angle and speeds up (example: water  air), the light will refract away from the normal the angle of refraction will be greater than the...

SNC2D – PHYSICS LIGHT & GEOMETRIC OPTICS 12.5 Total Internal Reflection  Total Internal Reflection RECALL  If light enters a second medium at an angle and speeds up (example: water  air), the light will refract away from the normal the angle of refraction will be greater than the angle of incidence 𝜃R 𝜃i  Total Internal Reflection TOTAL INTERNAL REFLECTION  As the angle of incidence increases, the angle of refraction will also increase  Eventually, the angle of refraction would be 90° (along the boundary between the two media) at this point, the angle of incidence is called the critical angle ()  Total Internal Reflection TOTAL INTERNAL REFLECTION  When the angle of incidence continues to increase (), the light is no longer refracted into the second medium (the light only reflects) this is known as total internal reflection the reflected ray obeys the laws of reflection ()  Total Internal Reflection APPLICATIONS OF TOTAL INTERNAL REFLECTION DIAMONDS  high index of refraction () means a low critical angle (24.4º)  when light rays enter a diamond, they experience several total internal reflections before travelling back into the air  this causes in the sparkle  Total Internal Reflection APPLICATIONS OF TOTAL INTERNAL REFLECTION FIBRE OPTICS  light is used to transmit information  the light remains in the glass fibre by reflecting off the inside surface – light is “trapped” inside  are used instead of metal wires because less signal loss immune to electromagnetic interference  Total Internal Reflection APPLICATIONS OF TOTAL INTERNAL REFLECTION TRIANGULAR PRISM  used in optical devices (cameras, binoculars, etc) since nearly 100% of light is reflected (mirrors lose due to absorption and deterioration)  can reflect at 90° or 180° based on orientation  Total Internal Reflection APPLICATIONS OF TOTAL INTERNAL REFLECTION RETRO-REFLECTORS  device that returns incident light back the way it came  used in road signs, bicycle reflectors, etc