# Evan's Space

## Demonstration of Reflection, Refraction and TIR using light source with a slit

Reflection of light using a mirror

Refraction of light using various shaped optical mediums

Total Internal Reflection (TIR) using a semi-circular perspex

For Total Internal Reflection (TIR) to occur:
1) angle of incidence i is greater than the critical angle c
2) the light is travelling from an optically denser medium towards a less dense medium

Click on this post for the explanation of TIR

## Total Internal Reflection (TIR) example 02

Solutions:

a) 38.8o      b) 41.8o

c) 51.2o . The ray does not emerge as total internal reflection has occurred. The angle of incidence is greater than critical angle and the light is traveling from a denser towards a less dense medium.

Click here to view the video tutorial for working and explanation for (a) and (b).

Click here to view the video tutorial for working and explanation for (c) and (d).

## Total Internal Reflection (TIR) example 01

Solutions:

a) Refraction     b) 48.6o     c) c = 41.8o     e) 70o

d) Total internal reflection has occured, as the angle of incidence is greater than critical angle and the light is traveling from a denser medium (glass) towards a less dense medium (air)

Click on the video tutorial for explanation and working for part (a) and (b).

Click on the video tutorial for explanation and working for part (c) to (e).

## An example of Total Internal Reflection

Some designer lightings like that one show in the video make use of total internal reflection. This was taken at Spring Maternity @NEX Jul 2011.

Each strand is actually make of transparent plastic-like material, which is flexible and has higher optical density than the air.

Recall the 2 conditions for total internal reflection to take place
1: light is traveling from denser medium (plastic) to the less dense medium (air)
2: angle of incidence is greater than critical angle

Hence from the centre light source, light can total internal reflection and comes out from the other end of each strand. There you have it! A unique designer lighting, just making use of physics!