3449577
Description
Flashcards by 18mariade8897, updated more than 1 year ago
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Created by 18mariade8897
over 9 years ago
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| Question | Answer |
| What is T.I.R? | Total Internal Reflection is when a ray of light hits a boundary between 2 materials of different densities and is reflected rather than refracted |
| What are the 2 conditions for Total Internal Reflection? | 1. The angle of incidence must be bigger than the critical angle 2. The light must be passing from a medium with a higher refractive index to a medium with a lower one e.g from water to air |
| What is the critical angle? | The critical angle is when the angle of incidence produces an angle of refraction of 90 degrees |
| What if the angle of incidence is greater than 90 degrees? | The larger the angle of incidence more of the light is reflected and less passes into the other medium. Therefore you get a weak reflection and good transmission into the other medium |
| What if you have a small angle of incidence? | If you have a small angle of incidence |
| What happens when the angle of incidence reaches the critical angle? | When this occurs there is no transmission of light into the other medium as it's all reflected and Total Internal Reflection is reached |
| Identify the 3 uses of Total Internal Reflection | 1. Fibre Optic cables in telecommunications 2. An endoscope - a camera used to see inside the body 3. Cable tv / local area networks |
| What are the 2 types of optical fibres used in telecommunications? | 1. Step-index fibre: The core is made from a type of glass whilst the outer layer has a lower refractive index 2. Graded-index fibre: The refractive index of the fibres gradually decreases as it moves outwards from the centre |
| How is T.I.R used in astronomy? | If the light from multiple galaxies or stars needed to be studied simultaneously, then fibre optics is needed. Each fibre receives light from a particular area in the sky which is turned into electrical signals and sent to a computer. |
| How does T.I.R apply to bicycle | Bicycle reflectors are made of "Corner-cube reflectors" which are designed to return light to its source. Although the mirrors look like they are coated in metal, they are made up of see through plastic which uses the principles of T.I.R to reflect light. |
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