Question

3. One problem with using optical fibers for communication is that a light ray passing directly down the center of the fiber takes less time to travel from one end to the other than a ray taking a longer, zig-zag path. Thus light rays starting at the same time but traveling in slightly different directions reach the end of the fiber at different times. This problem can be solved by making the refractive index of the glass change gradually from a higher value in the center to a lower value near the edges of the fiber. Explain how this reduces the difference in travel times.

Short answer

This reduces the difference in travel times is Larger index of refraction will slow the light down and it will get to the end of the fiber closer to the time the other light gets there.

Step-by-step solution

 Step1:Definition of light ray

When a light ray travels at an angle into a medium with a different refractive index, it refracts. This change in speed causes a shift in direction. Consider the movement of air into water as an example. As light continues to travel at a different angle, its speed decreases.

find reduces the different in travel time

Larger index of refraction $v=c/n.$will slow the light down and it will arrive at the end of the fibre closer to the time the other light arrives.