(c) In an optical fibre, if n 1 and n 2 are the refractive indices of the core and cladding, then which among the following, would be a correct equation? 

(i) n 1 < n 2  

(ii) n 1  = n 2  

(iii) n 1 << n 2

(iv) n 1 > n 2


Optical Fibres work on the principle of total internal reflection

The main conditions for total internal reflection are:

  • Light should travel from denser to rarer medium.
  • Angle of incidence should be greater than critical angle


The refractive index of the core is greater than the refractive index of the cladding.  


So the correct answer is (iv)

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Davneet Singh

Davneet Singh has done his B.Tech from Indian Institute of Technology, Kanpur. He has been teaching from the past 14 years. He provides courses for Maths, Science, Social Science, Physics, Chemistry, Computer Science at Teachoo.