33 - MasteringPhysics: Assignment Print View

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MasteringPhysics: Assignment Print View http://session.masteringphysics.com/myct/assignmentPrint?assig. .. 1 of 15 17/4/07 15:51 [ Assignment View ] E ð lisfræ ð i 2, vor 2007 33. The Nature and Propagation of Light Assignment is due at 2:00am on Wednesday, January 17, 2007 Credit for problems submitted late will decrease to 0% after the deadline has passed. The wrong answer penalty is 2% per part. Multiple choice questions are penalized as described in the online help. The unopened hint bonus is 2% per part. You are allowed 4 attempts per answer. The basics of light propagation and waves Understanding the Propagation of Light Learning Goal: To understand ray diagrams, as well as basic reflection and refraction problems. There are two ways of indicating, in a diagram, the path that light follows. One way is by using wavefronts (shown in blue); the other is by using rays (shown in red) . Wavefronts represent, in a schematic way, the successive peaks of the electromagnetic wave at a specific time. Light is a transverse wave; it moves perpendicular to the wavefronts. Rays are used to indicate the direction of motion of the light. Ray diagrams are typically used in problems where the wave nature of light is not important, as will be the case in geometric optics. Notice in the diagram that the wavefronts get closer together inside of the glass. This is because the speed of light in glass is less than that in air. The frequency of a wave does not change when it propagates through different media, even though its speed may change. (Waves can be neither created nor destroyed at the boundary between different media; hence, the number of waves that strike the boundary per unit time must equal the number of waves that leave the boundary per unit time.) Let be the wave's speed, its wavelength, and its frequency. These quantities are related via the equation . Note that, if the wave speed decreases, the wavelength must also decrease for the frequency to remain constant. Part A What is the wavelength of light in glass, if its wavelength in air is , its speed in air is , and its speed in the glass is ? Hint A.1 How to approach the problem Hint not displayed Express your answer in terms of , , and . ANSWER: = Answer not displayed Part B Part not displayed Part C Two important things happen to light when it strikes a transparent boundary: It gets reflected and it gets refracted. When you see your reflection in glass, you are seeing the result of reflection from a transparent boundary. In the figure , the ray moving toward the air/glass interface is called the incident ray. The ray leaving the boundary in air is called the reflected ray. The ray leaving the boundary inside the glass is [
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This note was uploaded on 11/02/2009 for the course MASTERING PHYS taught by Professor All during the Spring '09 term at Kettering.

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33 - MasteringPhysics: Assignment Print View

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