# 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

## To bend or not to bend?

Important concepts:
1) angle of incidence is the angle between the incident ray and normal
2) when the angle of incidence i = 0, light will pass through without bending

## Refraction of Light in Glass Block

Refraction is the bending of light as light travels from one medium to another medium of different refractive index.

As light travels from less dense medium (air) to the denser medium (glass), it bends towards the normal as the speed of light decreases in the medium.

The video below show how the refraction takes place in the glass block and how to position the needles in line.

<p>Refraction of Light – Glass Block + Needles from evantoh on Vimeo.</p>

## Refraction

This is not magic! As both the water and crystal balls have the same refractive index (optical density), light will pass through without bending as if both are of the same medium. Hence you are not able to see the crystal balls.