If you want to delay a pulse of light in a laser experiment, you can send the light through a long coil of fiber optic cable. Li
ght travels somewhat slower in the glass core of a fiber than it does in vacuum. We will approximate the speed of light in the fiber as 2.04 x 108 m/s. What length of fiber (in meters) should you use if you want to delay the arrival of light by 557 ns
For this exercise, the first thing we must notice is that the speed of the laser beam in the fiber is constant, so we can use the uniform motion relationships to find the necessary distance
v = d / t
let's reduce to SI units
t = 557 ns = 557 10⁻⁹ s
d = v t
d = 2.04 10⁸ 557 10⁻⁹
d = 1.136 102 m
d = 113.6 m
This is the distance of the fiber for the laser to arrive with the desired delay
