3.20
10 February 2011
14:56
· 3.20 describe the role of total internal reflection in transmitting information along optical fibres and in prisms
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| <<Total internal reflection.mpg>> | ||
| TIR
Optical fibres | ||
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<<TIR demo and uses of - interactive.swf>>
Applications of TIR using prisms
Periscope
Bicycle reflector
Binoculars
Applications of TIR using fibre optics
Endoscope
Communications networks (telephone and internet)
3.21
10 February 2011
14:56
· 3.21 explain the meaning of critical angle c
· You should already have learnt this from the keywords from this unit
· Tell the person next to you the definition now!
Answer
· The smallest angle of incidence for which Total Internal Reflection occurs
also acceptable:
· The angle of incidence for which the angle of refraction is exactly 90o
3.22
10 February 2011
14:56
· 3.22 know and use the relationship between critical angle, and refractive index:
sin c = 1 / n
sin c = 1 / n
c = critical angle (o)
n = refractive index (no units)
3.22 Plenary Answers
09 March 2012
09:46
Answers
Q1. What is the refractive index of glass that has a critical angle of 42o?
sin c = 1/n
sin 42 = 1/n
n = 1/sin 42
n = 1.5
Q2. What is the critical angle for diamond? (ndiamond = 2.4)
sin c = 1/n
sin c = 1/2.4
c = sin-1 0.417
c = 25o
3.14 to 3.22 Plenary questions, Pearson p.116 and 117
21 March 2012
12:57


