Transferring Information with Light

Instructor: David Wood

David has taught Honors Physics, AP Physics, IB Physics and general science courses. He has a Masters in Education, and a Bachelors in Physics.

Learn about how humans communicate using light. Internet, telephone audio, and home cinema signals -- we can do it all with light. Read about the various ways, and then complete a quiz.

Transferring Information with Light

What is light? You might think you know what light is, but you probably don't know the full answer. In everyday life, light is considered to be what your eyes can detect. But in physics, light goes far beyond that.

Light is any electromagnetic wave across the whole EM spectrum and includes visible light, radio waves, microwaves, infrared, ultraviolet, x-rays, and gamma rays. All of these things are light waves to a physicist. Each of them has a different wavelength and frequency (or color), but they're all electromagnetic waves.

The Electromagnetic Spectrum
The Electromagnetic Spectrum

In the modern world, we have a pretty good grasp of physics. We have a strong understanding of how the universe works, and we can use that understanding to do some amazing things. One thing we can do is send information using light. This information can be pictures and sound sent to a television, or data sent through an internet connection. Today we're going to talk about the various ways we can use light to transfer information.

Fiber Optics and Infrared

Perhaps the most successful way we've been able to use light to transfer information is fiber optics. These days, most information we want to send is digital; it's in computer language, made up of a bunch of zeros and ones continuing endlessly one after the other. We can send that information in lots of ways, but fiber optics is one of the more modern ones.

A fiber optic cable is a wire containing transparent materials that can carry light. The outside of the cable contains a material that will reflect the light, keeping it moving along the length of the cable. We send digital information through these cables using a bunch of light pulses. A strong pulse of light indicates a one, and no pulse indicates a zero. Through rapid changes in the light, you can send highly complex signals down the cable. These are most often used either for high speed internet connections, or for sending sound signals to home theater systems.

A Fiber Optic Cable
A Fiber Optic Cable

Usually infrared signals are sent along these fiber optic cables since these kinds of waves spread out the least and, thereby, lose the least amount of data during transmission.

Infrared Beams and Lasers

Infrared can also be used without a cable. The most common everyday example of this is a remote control. Pretty much every remote control in your home will use infrared beams to send its signals. When your point your remote control at the TV to change the channel, it's infrared that's taking the signal to your TV to be interpreted in a series of remote control codes (just a set of numbers).

Remote controls use infrared
Remote controls use infrared

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