[physics] refraction Flashcards
laws of refraction
- incident ray, refracted ray, and normal at the point of incidence all lie on the same plane
- for the 2 given media, the ratio of the sine of the angle of incidence to the sine of the angle of refraction is a constant
conditions of tir
- incident ray must travel from optically denser to optically less dense medium
- angle of incidence must be greater than critical angle
if from less dense medium to denser medium, speed and bending?
- less dense to denser medium
- slow down
- bend towards normal
3 equations to remember
refer to notes
larger refractive index slower or faster speed of light
slower
applications of tir
- glass prisms
- optical fibres (telecommunication, medicine)
what is optical fibre
- long, thin and flexible
- made of glass or plastic
- can carry information in the form of coded light pulses
what is the use of tir in optical fibres
transmit signals
what if the optical fibre becomes bent
light rays entering it will still be internally reflected at the boundary between the 2 refractive materials
advantages of using optical fibres over copper wires in telecommunications
- data transfer rate is ten to thousands times faster
- less signal loss
- lighter and cheaper
- carry much more information over long distances
- immune to electromagnetic intereference
advantages of using optical fibres in medicine
- thin and light, the endoscopes are kept small for minimally invasive examination and surgery
- flexible, the endoscopes can curve around obstacles when taking images inside the body
why use glass prisms
it is used to reflect light by TIR in some optical instruments like binoculars, periscopes and single lens reflex cameras
why use tir for glass prisms
it is a better light reflector than mirrors as they do not
- has a silvered surface that can wear off
- produce multiple reflections
