SNC2D1
Unit 2: Light and Geometric Optics (Chapter 11, 12 and 13)
Date:__________________
Name:_____________________
12.5 Total Internal Reflection
When light travels from one medium to another, usually, __________________________________________.
Light bends ____________________ when it travels from a medium that is more to less dense (Ex. water to air)
since light moves faster in the medium that is less dense.
Let’s consider a ray of light coming from water (medium 1) and travelling to air (medium 2).
If the angle of incidence is increased (θi); the angle of refraction ___________________ until θR reaches 90°.
At this point the angle of incidence is called the ___________. (The critical angle is different for every medium).
If the angle of incidence is increased passed the critical angle; there will be _____________  all of the light will
be ___________. We call this ___________________________________.
See figure 2 on page 526 of your text for a picture of total internal reflection of a laser beam in water.
some videos showing this:
https://www.youtube.com/watch?v=NAaHPRsveJk;
http://www.reading.ac.uk/virtualexperiments/ves/tir.html;
https://www.youtube.com/watch?v=s7w1Z1FCgwA&feature=related; https://www.youtube.com/watch?v=gDA_nDXM-ck
There are 2 conditions for TIR to occur:
1. The light must travel from a medium with a __________ to a medium with a ____________ value.
2. The angle of incidence must be ___________________________.
Diamonds sparkle due to:
1. Their __________________________ which results in a small critical angle of 24.4°.
2. The _________ (which allows for more reflections)
We see it sparkle as many light rays enter the diamond and undergo two total internal reflections.
Fibre Optics
1. Technology in which ________________________________________________
2. Used in ___________________________
3. The light entering this medium ______________ as it travels along the cable due
to Total Internal Reflection.
4. The cable must have a _________________________.
how fibre optic cables work: https://www.youtube.com/watch?v=0MwMkBET_5I
Cameras and binoculars
1. Cameras and binoculars use ___________ that have a ___________________ in order to
_________________ of the light internally
2. These prisms are used to __________________ of light
Ex. periscope
Homework: Read 12.5 p 526 – 531, Complete p. 531 # 1-3, 5, 8-9