Diffraction and Polar(HW5)

# Diffraction and Polar(HW5) - MasteringPhysics Assignment...

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[ Print View ] Physics 228 Spring 2008 Diffraction and Polarization (Ch. 36, 33.5) Due at 11:59pm on Wednesday, February 27, 2008 View Grading Details Using a Michelson Interferometer You are asked to find the index of refraction for an unknown fluid, using only a laser and a Michelson interferometer. A Michelson interferometer consists of two arms --paths that light travels down, which end in mirrors-- attached around a beam splitter. The beam splitter separates the incoming light into two separate beams and then recombines them once they return from the ends of the arms. The recombined beams are sent to a telescope, where their interference pattern may be observed in detail. Part A First, you must find the wavelength of the laser. You shine the laser into the interferometer and then move one of the mirrors until you have counted fringes passing the crosshairs of the telescope. The extremely accurate micrometer shows that you have moved the mirror by millimeters. What is the wavelength of the laser? Express your answer in nanometers, to four significant figures. Hint A.1 Relating wavelength and distance in a Michelson interferometer Hint not displayed ANSWER: = 632.8 Part B You now immerse the interferometer in a tank filled with some unknown liquid and carefully align the laser into the interferometer. You move the mirror until you count 100.0 fringes passing the crosshairs of the telescope. The micrometer indicates that the mirror has moved millimeters. What is the mystery fluid? Page 1 of 12 MasteringPhysics: Assignment Print View 5/8/2008 http://session.masteringphysics.com/myct/assignmentPrint?assignmentID=1116516

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Part B.1 Find the index of refraction Part not displayed ANSWER: water ( ) methanol ( ) ethanol ( ) acetone ( ) isopropyl alcohol ( ) saline ( ) Multislit Interference and Diffraction Gratings Learning Goal: To understand multislit interference and how it leads to the design of diffraction gratings. Diffraction gratings are used in modern spectrometers to separate the wavelengths of visible light. The working of a diffraction grating may be understood through multislit interference, which can be understood as an extension of two- slit interference. In this problem, you will follow the progression from two-slit to many-slit interference to arrive at the important equations describing diffraction gratings. A typical diffraction grating consists of a thin, opaque object with a series of very closely spaced slits in it. (There are also reflection gratings, which use a mirror with nonreflecting lines etched into it to provide the same effects.) To see how a diffraction grating can separate different wavelengths within a spectrum, we will first consider a "grating" with only two slits. Recall that the angles
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## This note was uploaded on 11/25/2010 for the course PHYSICS 228 taught by Professor Staff during the Spring '08 term at Rutgers.

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Diffraction and Polar(HW5) - MasteringPhysics Assignment...

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