{"id":10891,"date":"2020-12-18T08:47:32","date_gmt":"2020-12-18T03:17:32","guid":{"rendered":"https:\/\/cbselibrary.com\/?p=10891"},"modified":"2020-12-18T15:28:07","modified_gmt":"2020-12-18T09:58:07","slug":"measure-refractive-index","status":"publish","type":"post","link":"https:\/\/cbselibrary.com\/measure-refractive-index\/","title":{"rendered":"How do you Measure the Refractive Index?"},"content":{"rendered":"

How do you Measure the Refractive Index?<\/h2>\n
    \n
  1. The law of refraction states that:\n
      \n
    1. The incident ray, the refracted ray and the normal all lie in the same plane.<\/li>\n
    2. The ratio of the sine of the angle of incidence, i to the sine of the angle of refraction, r is a constant,
      \n\\(\\frac{\\sin \\,i}{\\sin \\,r}=\\text{ constant}\\)<\/li>\n<\/ol>\n<\/li>\n
    3. Refractive Index Formula:<\/strong> The value of this constant, \\(\\frac{\\sin \\,i}{\\sin \\,r}\\)\u00a0for a light ray passing through a vacuum into a given medium is called the refractive index<\/strong>, n of the medium. It is defined as:
      \n\"How<\/li>\n
    4. This relationship is also known as Snell\u2019s law<\/strong>.<\/li>\n
    5. (a) Refractive Index in terms of Speed of Light:<\/strong>
      \nThe refractive index of a medium may be defined in terms of the speed of light as follows
      \n\\( \\text{Refractive index }=\\frac{\\text{Speed}\\,\\,\\text{of}\\,\\,\\text{light}\\,\\,\\text{in}\\,\\,\\text{vacuum}}{\\text{Speed}\\,\\,\\text{of}\\,\\,\\text{light}\\,\\,\\text{in}\\,\\,\\text{medium}} \\)
      \n\\( \\text{ }\\!\\!\\mu\\!\\!\\text{ }=\\frac{c}{v} \\)
      \n(b) Refractive Index in terms of Wavelength:<\/strong>
      \nSince the frequency (\u03bd) remains unchanged when light passes from one medium to another, therefore,
      \n\\( \\text{ }\\!\\!\\mu\\!\\!\\text{ }=\\frac{c}{v}=\\frac{{{\\lambda }_{vac}}\\times \\nu }{{{\\lambda }_{med}}\\times \\nu }=\\frac{{{\\lambda }_{vac}}}{{{\\lambda }_{med}}} \\)
      \n(c) Relative Refractive Index:<\/strong>
      \nThe relative refractive index of medium\u00a02 with respect to medium 1 is defined as the ratio of speed of light (\u03bd1<\/sub>) in the medium 1 to the speed of light (\u03bd2<\/sub>) in medium 2 and is denoted by 1<\/sub>\u00b52<\/sub>. Thus,
      \n\\(_{1}{{\\text{ }\\!\\!\\mu\\!\\!\\text{ }}_{\\text{2}}}=\\frac{{{v}_{1}}}{{{v}_{2}}}=\\frac{{{\\lambda }_{1}}}{{{\\lambda }_{2}}}=\\frac{{{\\mu }_{2}}}{{{\\mu }_{1}}}\\)
      \nAs refractive index is the ratio of two similar physical quantities, so it has no unit and dimension.<\/li>\n
    6. Factors On Which The Refractive Index Of A Medium Depends Are:<\/strong>\n
        \n
      1. Nature of the medium.<\/li>\n
      2. Wavelength of the light used.<\/li>\n
      3. Temperature<\/li>\n
      4. Nature of the surrounding medium.<\/li>\n<\/ol>\n

        It may be noted that refractive index is a characteristic of the pair of the media and also depends on the wavelength of light, but is independent of the angle of incidence.<\/li>\n

      5. The angle of refraction of light depends on the refractive index of the mediums and the angle of incidence.<\/li>\n
      6. Figure shows how the angle of refraction, r depends on the angle of incidence, i when light travels from air into three different media. Mediums and media are the plural forms of medium.
        \n\"How<\/li>\n
      7. For a given angle of incidence, i the angle of refraction, r becomes smaller in a denser medium. As the decrease of the speed of light is greater in a denser medium, the light ray will bend more.<\/li>\n
      8. When the angle i and the angle r are expressed as sin i and sin r respectively, their relationship is as shown in Figure.
        \n\"How<\/li>\n
      9. The gradient of the graph of sin i against sin r shows how much the light is bent in the denser medium. This gradient is the value of the refractive index, n of a medium.<\/li>\n
      10. Table shows the refractive indices of some substances. Substances which are optically denser have a larger refractive index and the light rays bend or refract more in these substance.
        \n\"How<\/li>\n<\/ol>\n

        People also ask<\/strong><\/p>\n