. Light, a textbook for students who have had one year of physics. kind that MN reflects,for their planes of incidence areparallel. But if XY be turnedabout the ray CB as an axisthrough 90°, to the position shownat XY, their planes of incidencebecome perpendicular, and thelight reflected by MX cannot bereflected at XY! Similarly a glass Figure Ul plate can be used to test any beam of light to see whether itis plane polarized or not. It is only necessary to set the plateso that it receives the beam at the angle of polarization, andthen turn it about the incident beam as an axis, so as to keepth
. Light, a textbook for students who have had one year of physics. kind that MN reflects,for their planes of incidence areparallel. But if XY be turnedabout the ray CB as an axisthrough 90°, to the position shownat XY, their planes of incidencebecome perpendicular, and thelight reflected by MX cannot bereflected at XY! Similarly a glass Figure Ul plate can be used to test any beam of light to see whether itis plane polarized or not. It is only necessary to set the plateso that it receives the beam at the angle of polarization, andthen turn it about the incident beam as an axis, so as to keepthe angle of incidence always equal to the polarizing angle. If,for any position of the plate, the reflected light vanishes, thebeam in question is polarized in a plane perpendicular to theplane of incidence. Problems. 1. What must be the angle a, figure 108, in order that theimages b and c shall lie twice as intense as the images a andd? 2. Prove that, when light strikes a glass plate at thepolarizing angle, the reflected and refracted rays are at 222 LIGHT 3. Find the angle of polarization for glass whose index ofrefraction is 4. Show that light that lias gone through a prism spectro-scope must be partly polarized. In what plane will be themaximum polarization \ CHAPTER XIII. 112. Methods of polarizing light.—113. The Nicol prism.— prisms.—115. Crossed Nicols and crystal plate.— polarization.—117. Circular polarization.—118. Rotation of theplane of polarization.—119. Magnetic rotation.—120. The rings-and-brushes phenomenon.—121. The nature of elliptic and circular polar-ization. 112. Methods of polarizing light.—For many purposes inexperimental optics, as well as in its industrial applications, itis desirable to obtain a strong beam of plane polarized simple block of calcite does not answer the suppose, for ittransmits two beams with mutually perpendicular planes ofvibration, and these are parallel in
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectlight, bookyear1921
