You are given kerosene, turpentine and water. In which of these does the light travel fastest? Use the information given in Table 10.3

Table 10.3 NCERT - Refractive Index of Some Media.jpg

Answer

We know that,

Refractive index of the medium = Speed of light in air / Speed of light in the medium 

 

Therefore,

Speed of light of the medium = Speed of light in air / Refractive index in the medium 

 

Since Speed of light in air is always constant

 

Hence,

Speed of light in the medium = Constant/ Refractive index of the medium

 

Hence, we can say that

Lower refractive index of the medium, the higher is the speed of light.

 

The refractive index of

  • Kerosene is 1.44
  • Turpentine is 1.47
  • Water is 1.33

 

Since the refractive index of water is the lowest among the three, 

Speed of light in water would be higher than that in kerosene and turpentine.

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CA Maninder Singh is a Chartered Accountant for the past 14 years and a teacher from the past 18 years. He teaches Science, Economics, Accounting and English at Teachoo