Zusammenfassung der Ressource
Total Internal Reflection
- Optical Fibres
- carry visible light over long distances
- work (because of total internal reflection) by bouncing waves off the sides
of a thin inner core of glass or plastic
- wave enters one end of the fibre and is reflected
repeatedly until it emerges at the other end
- Critical Angle
- dense material with a high refractive index
- low critical angle
- Critical angle of glass: 42*
Critical angle of diamond: 24*
- why diamonds are so sparkly
- material with high refractive index
- will totally internally reflect more light
- more light will be incident at an angle bigger than the critical angle
- Endoscopes
- a thin tube containing optical fibres
- lets surgeons examine inside the body
- consists of two bundles of optical fibres
- one: carry light to the area of interest
- other: carry an image back
so that it can be viewed
- image seen through an eye-piece or
displayed as a full-colour on a TV screen
- Big Advantage
- Surgeons can perform many operations by only
cutting teeny holes in people (called keyhole surgery)
- happen when
- a wave travels through a dense substance like glass
or water towards a less dense substance like air
- if the angle of incidence is
- Less than Critical angle
- most of the light passes out
- little bit is internally reflected
- equal to Critical angle
- emerging ray comes out along the surface
- quite a bit of internal reflection
- greater than Critical Angle
- No light comes out
- All internally reflected i.e. total internal reflection