Total Interal Reflection and fibre optics Flashcards
What is total internal reflection?
When a wave travelling inside a denser medium reflects off the boundary with another medium, and so stays inside the original material.
What is the critical angle?
Smallest angle of incidence for which TIR takes place.
45 degrees from normal line
What are the requirements for total internal reflection?
- The angle of the light is greater than the critical angle
- The light is travelling in the denser of the two materials
What are optic fibres?
Very fine glass cables
Uses of optic fibres
Transmit large amounts of information
Help doctors peer inside the body without cutting the patient open
How do optic fibres work?
Waves travel along optical fibres by TIR. They enter the fibre ad hit the edge at an angle greater than the critical angle. They reflect off the inside of the glass fibre until they reach the other end.
How are optic fibres suited to communication?
With fibre optic broadband, pulses of visible light or infrared are sent down optic fibres. This allows large amounts of data to be sent very quickly. Generally much faster than using normal phone lines.
What is an endoscope?
a kind of probe using fibre optics to produce an image of the inside of the body
How does an endoscope work?
Inside an endoscope there are several bundles of optic fibres. The endoscope is inserted into the body and visible light is sent down one of the bundles of cables. The light illuminates the inside of the body and is then reflected back down a separate bundle of fibres. The doctor either looks along the fibre or the image is sent to a TV screen, providing a clear picture of the patient’s insides.
Which is denser: air or glass?
glass
Which is denser: air or water?
water
Which is denser: water or glass?
glass
