Refraction and partial reflection

1. Refraction and partial reflection Most of the light is refracted air glass Less than 42

2. Total internal reflection This is total internal reflection air glass More than 42

3. The critical case This is the border line case air glass Critical angle = 420

4. Optical fibre out Glass fibre in Repeated total internal reflection

5. The endoscope

6. Endoscopy

7. Using T.I.R - endoscope • Optical fibres are used to examine the stomach and lungs • A fibre carries light into the stomach and illuminates it • A second fibre carries the light from the stomach to a camera • Internal examination can be made

8. An endoscope for examining ears

9. Optical fibre can carry many signals

10. Optical fibres for communication • Optical fibres carry signals in the form of light waves • Compared with copper wire • They can carry many different signals at the same time • There is less signal loss and less interference

11. Using T.I.R. – right angle prisms T.I.R. here since the angle of incidence = 45o > C (42o)

12. Periscopes This is used by cars towing caravans

13. Cats eyes in the road