A cross-section of a ‘light pipe’ made of a glass fiber of refractive index 1.68. The outer covering of the pipe is made of a material of refractive index 1.44. What is the range of the angles of the incident rays with the axis of the pipe for which total reflections inside the pipe take place, as shown in the figure?

1. \(0^\circ<i<45^\circ\)
2. \(0^\circ<i<60^\circ\)
3. \(45^\circ<i<75^\circ\)
4. \(45^\circ<i<90^\circ\)