Fiber Optics Lesson

Fiber Optics at a glance

Background

Have you ever wondered how your internet connection works or how doctors see inside your body with cameras? Fiber optics play a crucial role in these technologies! In this lesson, students will dive into the science of fiber optics, which involves sending light through thin, transparent fibers to carry information.

Fiber optics are like super-thin strands of glass—about as thick as a human hair. These strands are bundled together to form optical cables that transmit light signals between two points. But how does the light stay inside these tiny glass fibers? In this hands-on lesson, students will explore the fascinating world of fiber optics, learning how light can travel through tiny strands of glass and be used to transmit data, voice, and images over long distances. By experimenting with a fiber optic cable and an LED light source, students will see how light is guided through the cable and discover the science behind this technology.

Lesson Objective

Students will investigate how fiber optics transmit light and the principle of total internal reflection using a simple fiber optic cable and LED light source. This experiment demonstrates how light travels through a thin fiber and how bending the fiber affects light transmission.

Experiment Description

By connecting an LED light source to one end of a plastic fiber optic cable, students will observe how light is transmitted through the cable and how it exits from the other end. They will also test how bending or knotting the cable impacts the light's visibility.

Materials List

LED key chain light source
Plastic fiber optic cable (PMMA)
Scissors (for cable adjustments, if needed)

Safety Precautions

The LED light is a choking hazard.

Handle the LED light source with care and avoid bending the fiber optic cable excessively to prevent damage.

The Experiment

Place the LED lens tightly against the end of the cable where the fibers are flush with the black protective coating.

Turn on your LED light source and observe the other end of the cable where the fiber strands are exposed. You will notice that the light is transmitted out the ends of the fibers, but if you look from the side you will observe little or no light.

Can you tie your cable in a single knot? Does it affect the light coming out the other end? You might expect a beam of light, traveling in a clear glass pipe, simply to leak out of the edges.

But if light hits glass at a really shallow angle, it reflects back in again — as though the glass were really a mirror. This phenomenon is called total internal reflection.

It's one of the things that keeps light inside the pipe. And because the cladding does not absorb any light from the core, the light wave can travel great distances.