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© Boardworks Ltd 2003 Waves: Total Internal Reflection and Communication Give the meaning of critical angle Describe internal and total internal reflection Recall and use the definition of refractive index n in terms of speed Recall and use the equation sin i /sin r = n Describe the action of optical fibres particularly in medicine and communications technology
© Boardworks Ltd 2003 Reflected ray Total Internal Reflection Incident ray Refracted ray Angle i Angle r At what angle of incidence did the ray change from refraction to reflection? It depends upon the material you used.
© Boardworks Ltd 2003 Simulation of a ray of light passing through a semi-circular glass block
© Boardworks Ltd 2003 Total Internal Reflection This angle is called the critical angle [ c] i < c Refraction i = c Critical case i > c Total Internal Reflection [TIR] Different materials have different critical angles. Diamond has the lowest at 24º which is why it reflects so much light.
© Boardworks Ltd 2003 The Critical Angle How does refractive index affect the critical angle? The greater the refractive index the smaller the critical angle. MaterialRefractive index Critical angle Glass Water Diamond 42° 49° 24° 1.5 1.33 2.4 Research the missing values below and then make a conclusion…
© Boardworks Ltd 2003 Total Internal Reflection Optical fibres, that are used in communication, use total internal reflection. A beam of light enters the optical fibre…. …NOTE how it is refracted as it enters the fibre… …it travels down the fibre through repeated total internal reflections. What are the applications of total internal reflection? You could be asked to draw on the path of the beam in an exam.
© Boardworks Ltd 2003 Optical versus electrical Research why communications systems now use optical fibres instead of copper wires, use the table below to help you. OpticalElectrical Information Attenuation Interference Cost Carry moreCarry less LessMore NoYes MoreLess How is attenuation solved in optical and electrical fibres? Regenerators for electrical cables Repeaters for optical fibres
© Boardworks Ltd 2003 Digital and analogue What is the difference between a digital signal and an analogue signal? Digital signals can only be in one of two states, e.g. 0 or 1. Analogue signals are a continuously changing variable. What could they look like graphically?
© Boardworks Ltd 2003 ADVANTAGES Signals are clearer less susceptible to noise. Can be used quickly by computers. Carry digital signals using electromagnetic waves which travel at the speed of light. Carry much more information. Digital hardware is much smaller. Easier to send over long distances. DISADVANTAGES Digital hardware is expensive at the moment. Although digital signals are unaffected by electrical interference, they don’t give a complete signal [just lots of samples] - some people feel that analogue vinyl records sound better than digital CDs for this reason. What is noise? Noise is any unwanted information. Examples of noise are? Electrical storms and random thermal noise. Which signal is most prone to noise? Analogue Which signal carries the most information? Digital Digital compared to Analogue
© Boardworks Ltd 2003 Communication systems Communication systems include the same basic components. You need to be able to define/describe the following: Encoder Amplifier Decoder Modulator Transmitter Receiver Transducer Storage
© Boardworks Ltd 2003 Definitions ComponentFunction Encoder Decoder Modulator Transmitter Receiver Storage Transducer Amplifier Changes information into readable form Allows wave to carry impulses AM/FM Changes information to original form Stores information e.g. CD, DVD, tape Makes oscillations Collects information Changes information into electrical form or the other way round (microphone, speaker) Increases intensity of received waves
© Boardworks Ltd 2003 Which of the following is not a use of total internal reflection? A.Periscopes B.Endoscopes C.Fibre optic communication D.Mirrors
© Boardworks Ltd 2003 What does attenuation mean? A.Strengthening B.Increasing C.Larger D.Weakening
© Boardworks Ltd 2003 KS4 Waves: Total Internal Reflection and Communication.
© Boardworks Ltd of 20 © Boardworks Ltd of 21 KS4 Physics Total Internal Reflection and Communication.
© Boardworks Ltd 2003 KS4 Waves: Total Internal Reflection and Communication LEARNING OUTCOMES: Describe what happens to light incident on a perspex/glass-air.
1 IGCSE Physics Waves. 2 Lesson 8 – TIR and optical fibres Aims: To recall the meaning of critical angle c To recall and use the relationship between.
© Boardworks Ltd of 35. © Boardworks Ltd of 35.
COLLEGE FOR PROFESSIONAL STUDIES TOPIC OF PRESENTATION OPTICAL FIBRE.
Total Internal Reflection When light passes from a medium of larger refractive index into one of smaller refractive index (i.e., water to air), the refracted.
Total Internal Reflection. Can occur when light inside a glass block hits the edge at certain angles Remember – if light hits the boundary between two.
1 of 28© Boardworks Ltd 2006 Multiple-choice quiz.
Next page. The topics in this unit are: 1 – Types of waves 2 – Describing waves 3 – Wave equation 4 – Reflection of waves 5 – Refraction 6 – Diffraction.
By the end of this presentation, you should be able to: Recognise diagrams showing TIR Recall what conditions must be met in order for TIR to occur. Draw.
Lasers and Optics LO: to be able to calculate the refractive index using the critical angle of a substance.
Total Internal Reflection. Remember – when light goes from a more dense medium to a less dense medium it speeds up & bends away from the normal Remember.
Fiber Optic Transmission SL/HL – Option F.3. Reflection/Refraction Reflection – A wave encounters a boundary between two mediums and cannot pass through.
Total Internal Reflection (TIR ) from STAO’s ScienceWorks Gr. 10 Optics Survival CD Lesson 13.
TOTAL INTERNAL REFLECTION and the CRITICAL ANGLE.
P6 – The Wave Model of Radiation. Waves A wave consists of disturbances that transfer energy in the direction that the wave travels, without transferring.
1 of 34© Boardworks Ltd of 34© Boardworks Ltd 2009.
Light Refraction of Light. Learning Objectives You will learn to recall and use the terms used in refraction, including normal, angle of incidence and.
Refraction: from air to glass These lines are the crests of waves or WAVEFRONTS: the distance between successive wave fronts is called the WAVELENGTH Glass.
Noadswood Science, Optics To be able to calculate the refractive index using the critical angle of a substance Thursday, August 06, 2015.
Refraction – Learning Outcomes Define refractive index. Demonstrate refraction. State the Laws of Refraction. Solve problems about refraction.
Waves Waves can transfer energy and information without a net motion of the medium through which they travel. They involve vibrations (oscillations) of.
P1f(ii) Data Transmission You will learn about: How Optical Fibres are used How interference is reduced
PHYSICS – Total Internal Reflection and Lenses. LEARNING OBJECTIVES Core Describe the formation of an optical image by a plane mirror, and give its characteristics.
The electro-magnetic spectrum
When light rays hit a smooth surface, it gets reflected. A plane mirror has a flat surface. What are the characteristics of an image formed by a plane.
The Critical Angle and Total Internal Reflection.
Do now! Can you discuss with your partner all the things you can remember about the WAVES topic (topic 3)
IB Physics Option F – Fibre Optics Mr. Jean. The plan: Video clip of the day Fibre Optics –https://ibphysics2016.wikispaces.com/Option+ C+-+Imaginghttps://ibphysics2016.wikispaces.com/Option+
PHYSICS – Reflection and Refraction. LEARNING OBJECTIVES Core Describe the formation of an optical image by a plane mirror, and give its characteristics.
Wave Model of Radiation Revision. Waves Waves are disturbances that transfer energy in the direction of the wave without transferring matter. Waves are.
The Refraction of Light SNC2P – Optics. Refraction Refraction: the bending or change in direction of light when it travels from one medium into another.
Fiber Optic Transmission SL/HL – Option C.3. Reflection/Refraction Reflection – A wave encounters a boundary between two mediums and cannot pass through.
LIGHT Refraction is the change in direction of light when it passes from one medium to another.
REFRACTION (Bending of Light) Light slows down or speeds up when it enters and leaves another material.
KEYWORDS: refraction, angle of incidence, Angle of refraction, refractive index KEYWORDS: refraction, angle of incidence, Angle of refraction, refractive.
Introduction to Fiber Optics. What are optical fibers Thin strands of pure glass Carry data over long distances At very high speeds Fiber can be bent.
Refraction 1.Explain how refraction is the result of a change of speed 2.Explain what critical angle and T.I.R.. mean 3.Explain how optical fibres use.
24/06/2016 OCR Additional Science The Wave Model of Radiation W Richards A slideshow that covers the entire OCR 21 st Century 2006 Syllabus “Wave Model.
Refraction pg 222 – 236. 1) Principles of Refraction 2) Snell’s Law & Refractive Index 3) Total Internal Reflection 4) Optical Fibres.
Fiber Optic Transmission SL/HL – Option F Mr. Jean.
Slow fast Light passing from a medium in which it is ________ to one in which it is __________________ : 11 22 refracted reflected Now _______________.
P1d(ii) Light and Lasers You will learn about: Total Internal Reflection (TIR) How optical fibres are used in medicine and communications
Optical Communication From Sound to Light and Back.
UNIT TWO LIGHT AND GEOMETRIC OPTICS Chapters
AVERAGE SPEED When calculating the AVERAGE SPEED of an object you need to know the DISTANCE travelled by the object and the TIME taken to travel that distance.
Quiz 2: Sunday 11 th October ( Refraction & Diffraction) Test 1: Sunday 18 th October (Chapter 13 & 14)-All.
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