Visible Light Waves

Visible Light Waves

 

 

Types of Light

To understand light you have to know that what we call light is what is visible to us. Visible light is the light that humans can see. Other animals can see different types of light. Dogs can see only shades of gray and some insects can see light from the ultraviolet part of the spectrum. The key thing to remember is that our light is what scientists call visible light.

Scientists also call light electromagnetic radiation. Visible light is only one small portion of a family of waves called electromagnetic (EM) radiation. The entire spectrum of these EM waves includes radio waves, which have very long wavelengths and both gamma rays and cosmic rays, which are at the other end of the spectrum and have very small wavelengths. Visible light is near the middle of the spectrum.

It's all Energy

The key thing to remember is that light and EM radiation carry energy. The quantum theory suggests that light consists of very small bundles of energy/particles; it's just that simple. Scientists call those small particles photons, and the wavelength determines the energy and type of EM radiation, and the number of photons tells you how much radiation there is. A lot of photons give a brighter, more intense type of light. Fewer photons give a very dim and less intense light. When you use the dimmer switch on the wall, you are decreasing the number of photons sent from the light bulb. The type of light is the same while the amount has changed.

Different Speeds of Light?

As far as we know, all types of light move at one speed when in a vacuum. The speed of light in a vacuum is 299,792,458 meters per second. That speed is really fast, but even when you're traveling that fast, it takes a while to get places in space. It takes about seven minutes for light from the Sun to reach Earth. It takes over four years for the light from our Sun to get to the nearest star. It would take a particle of light over 100,000 years to get from one side of our galaxy to the other side. All of those values are light moving through a vacuum. You can slow light down in other substances such as the atmosphere, water, or a diamond. Light moves at about 124,000,000 meters per second (less than half the speed in a vacuum) in a diamond.

Communications

 

Communications

One of the great changes to our world over the past 100 years has been the invention of electronic communications. It all started with the telegraph and since then new inventions and innovations have created an information age that includes smart phones and high definition video over the internet.

Telegraph

The invention that got electronic communications started was the telegraph. It was invented by Samuel Morse in 1836. He also developed the Morse Code which allowed the signals that the telegraph sent over the wires to represent words and phrases.

Telephone

Around 40 years after the telegraph, Alexander Graham Bell received the patent for the telephone. Now instead of just beeps of sound, a person's voice could be transmitted over long distances of electric wires. Later inventions like faxes and modems would allow other information to pass over the same wires. Large switching networks were built throughout the world allowing telephones in nearly every home to connect with each other.

Fiber optic tubes of glass use light pulses to communicate

Fiber Optics

As the amount of information has grown, more and more data needs to be transmitted over long distances. One of the ways to send data faster is with fiber optics. Fiber optics are long skinny tubes (like wires) made of glass. Instead of electricity they transmit light. Light can travel at much faster speeds and over longer distances than electrical pulses. There are fiber optic connections today that can send 100 billion signals per second!

Radio Frequency

Radios have been used for a long time, but in the 1990s cell phones started to become popular. Cell phones send information using radio frequencies through the air. New technologies have allowed for faster signals and even video to be sent to and from cell phones.

Cell phones use radio frequencies to communicate through the air

Internet

Perhaps the most important invention in the area of electronic communications during recent times is the internet. The internet is made up of millions of electrical and fiber optic links. These links form a network that allows information to get passed and "switched" all over the world. More information is now available at your fingertips and on your computer at home than you could hope to read in a lifetime.

Fun facts about Electronic Communications

• There are around 250 billion emails sent every day. Around 80% of these are spam.
• Around 20 hours of video are uploaded to YouTube every minute.
• Fiber optics are good because they use less energy and are better for the environment than electrical wires. They are also very resistant to weather.
• The first telephone pole was built in 1876.
• There are over 4 billion cell phones in the world. Over 100 million cell phones are thrown away every year.
• The first cell phone was invented by the company Motorola.