9.5 Preliminary Assignment I) A plane mirror is used to trace out an incident be
ID: 1784755 • Letter: 9
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9.5 Preliminary Assignment I) A plane mirror is used to trace out an incident beam and a reflected beam. The angle of incidence is measured to be (12.5±0.5)" and the angle of reflection is measured to be (13.0±0.5)". Do these agree within uncertainty? A ray is incident upon a Plexiglas block. The angle of incidence is (22.0± 1.0). The refracted ray is measured to be (15.0±1.0)". 2) A) Use Snell's law to calculate the index of refraction for the Plexiglas (including uncertainty). (Hints: Note the uncertainty of the angle in the propagation formula must be in units of Radians. Also, use the error propagation formulas for functions See the lab manual introduction.) B) Compare n, as calculated in part A) with the accepted value of n, for Plexiglas of 1.5.Explanation / Answer
1] For a plane mirror, the angle of incidence must be equal to the angle of reflection.
Therefore, the error in angle of incidence will be equal to the error in angle of reflection.
Since the maximum angle of incidence can be 12.5+0.5 = 13o and minimum can be 12.5-0.5 = 12o therefore, the angle of reflection should be between 13 and 12 including its error. Since the maximum angle of reflection is 13+0.5 = 13.5o which falls beyond the maximum permissible angle of reflection of 13o [since angle of incidence = angle of reflection] therefore, this does not agree within the uncertainty.
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