Light is, therefore, essentially completely reflected as it passes through the tube. We have answered a large part of the question of how the significant portions of information-carrying light can enter a light guide and be transmitted with little loss. We now turn to some of the other practical aspects of low-loss light guides. A light guide would not be very useful if it had to follow a perfectly straight path. One of the advantages of optical fibers is their flexibility.
Fibers can be bent around obstacles and still transmit light.
Fill the bottle with water and, add a few drops of milk to slightly scatter the laser's light. Point the laser beam through the water and out the pin hole. Observe its path straight through the water and out along the bending stream. Directions are provided in Appendix 12. Guiding light along a curved path.