Posterous theme by Cory Watilo

 

 

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

 

 

<<Total internal reflection.mpg>>

 

TIR

Optical fibres

 

<<TIR demo and uses of - interactive.swf>>

Applications of TIR using prisms

Periscope

Image001

 

Bicycle reflector

Image002

 

Binoculars

Image003

 

Applications of TIR using fibre optics

Endoscope

Image004

 

Communications networks (telephone and internet)

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Plenary Questions.pptx (56 KB)
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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

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3.14 to 3.22 Plenary questions, Pearson p.116 and 117

21 March 2012

12:57

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