question_answer

In figure, the optical fiber is \[l=2\text{ }m\] long and has a diameter of \[d=20\mu m\]. If a ray of light is incident on one end of the fiber at angle \[{{\theta }_{1}}=40{}^\circ ,\]the number of reflections it makes before emerging from the other end is : (refractive index of fiber is 1.31 and \[sin\text{ }40{}^\circ =0.64)\]

Answer:

57000