light traveling in air strikes on the core area of the fiber end surface at an angle is 34.5 degree where it is measured btween the incoming ray and...

(a) what is the refractive index of the core of the fiber. (b) what are the NA and the maximum acceptance angle max of this fiber? (c) when light is coupled between two fibers, there can be an air gap between fibers. Explain how the refractive index matching angle1.4 can help to reduce the loss.