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Description
Flashcards by 18faishasu, updated more than 1 year ago
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Created by 18faishasu
over 9 years ago
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| Question | Answer |
| What is total internal reflection? | Total internal reflection is when a light ray hits the boundary between two materials of different densities and is reflected rather than refracted. |
| What must happen for total internal reflection to occur? | 1) The angle of incidence must be greater than the critical angle. 2) The light must be passing from a medium with a higher refractive index to a medium with a lower refractive index. |
| What is the critical angle? | The critical angle is when the angle of incidence produces an angle of refraction of 90° (or refraction along the boundary). |
| How do you calculate the critical angle? | where 0c is the critical angle, and nr and ni are refractive indexes. |
| How do you calculate the critical angle if light is passing from x medium into air? | because 1 is the refractive index of air. |
| What material gives the smallest critical angle? | Diamond. |
| What can total internal reflection be used for? | 1) Fibre optic cables. 2) Prismatic optical instruments. 3) Bicycle reflectors. |
| How is total internal reflection used in optical fibres? | |
| What are optical fibres used for? | Optical fibres are used in high-speed communications, such as cable TV and broadband. |
| What two types of optical fibres are used in telecommunications? | 1) Step index fibre - the core is uniform with one refractive index while the outer cladding has a lower index. 2) Graded index fibre - the refractive index of the material gradually decreases outwards from the centre. |
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