A light ray from air is incident (as shown in figure) at one end of a glass fibre (refractive index,
μ=1.5) making an incidence angle of 60 on the lateral surface, so that it undergoes a total internal reflection. How much time would it take to reverse the straight fiber of length 1 km?
![1157628_d47e182d7c4b4efd952e0ba1f521ffc3.png](https://search-static.byjusweb.com/question-images/toppr_invalid/questions/1157628_d47e182d7c4b4efd952e0ba1f521ffc3.png)