# hw13sols - MasteringPhysics 5/8/08 2:23 PM Assignment...

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5/8/08 2:23 PM MasteringPhysics Page 1 of 7 http://session.masteringphysics.com/myct Assignment Display Mode: View Printable Answers Physics 202 Assignment 13 Due at 11:00pm on Wednesday, April 30, 2008 View Grading Details Total Internal Reflection Conceptual Question Description: Simple conceptual question about the possibility of total internal reflection when a ray of light is incident on various interfaces. (ranking task) Consider scenarios A to F in which a ray of light traveling in material 1 is incident onto the interface with material 2. Material 1 ( ) Material 2 ( ) A air (1.00) water (1.33) B water (1.33) air (1.00) C diamond (2.42) air (1.00) D air (1.00) quartz (1.46) E benzene (1.50) water (1.33) F diamond (2.42) water (1.33) Part A For which of these scenarios is total internal reflection possible? Hint A.1 Total internal reflection Total internal reflection occurs when, mathematically, the refracted angle is 90 or greater. This means, physically, that there is no refracted ray. Therefore, all of the light is reflected. Hint A.2 Angle of refraction Total internal reflection is only possible if the refracted ray is bent farther from the normal than the incident ray is from the normal. Part A.3 Determine the role of the indices of refraction Snell's law says that for a light ray passing from region 1 to region 2, , where is the angle of the incident ray from the normal, and is the angle of the refracted ray from the normal. If , meaning that the refracted ray is bent farther from the normal than the incident ray, what is the relationship between and ? ANSWER: This means that the refracted ray is farther from the normal than the incident ray only when the ray travels from a region of larger index into a region of smaller index of refraction. List all correct answers in alphabetical order. For example, if scenarios A and E are correct, enter AE . ANSWER: BCEF [

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5/8/08 2:23 PM MasteringPhysics Page 2 of 7 http://session.masteringphysics.com/myct Part B For the scenarios in which total internal reflection is possible, rank the scenarios on the basis of the critical angle, the angle above which total internal reflection occurs. At this angle, the refracted ray is at 90 from the normal. Part B.1 Apply Snell's law At the critical angle, the refracted ray is at 90 from the normal. Therefore, Snell’s law can be used to determine the critical angle. Snell's law states that , where is the angle of the incident ray from the normal, and is the angle of the refracted ray from the normal. Solve this equation for the sine of the critical angle . Express your answer in terms of and . ANSWER: = Since increases as increases, the relative ranking of the critical angle will be the same as the relative ranking of , which is equal to . Rank from largest to smallest. To rank items as equivalent, overlap them.
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## This note was uploaded on 08/26/2009 for the course PHYS 4ABCD taught by Professor All during the Fall '08 term at Foothill College.

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hw13sols - MasteringPhysics 5/8/08 2:23 PM Assignment...

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