Diagrams 2

Wavelength on the Electromagnetic Spectrum

Lets begin by looking at the wavelengths in the visible spectrum. The ultraviolet waves are the shortest. They are four tenths of a micrometer. Since of micrometer is one millionth of a meter or .000001 and the violet waves are four tenths of that, it would be .0000004 meters. It might make better sense as .0004 of a millimeter. In other words, violet light would have 4 million waves per millimeter.

Red light, on the other hand, would have 7 million waves per millimeter. They are almost twice as long. You can understand why scientists get accustomed to using and thinking in powers of 10. This chart from NASA is very helpful

Making sense of Wavelengths on the Electromagnetic SpectrumThis electromagnetic spectrum includes the visible spectrum and more.

Lets go back to the basic organization of the chart. Starting on the left, we find gamma-Rays and then X-Rays with the very shortest waves (no wonder X-Rays could pass through our bodies).

As we move along the scale, through visible colors, infrared (some of which is heat), to microwaves and then radio and TV waves, the waves get longer and longer. The different lengths are astonishing.

The basic units here are imicrometers (1 millionth of a meter) We can find a millimeter on the meter stick but it’s tiny, one tenth of a centimeter.

But we aren’t talking just about micrometers. We begin with 10 to the -6  micrometers. That’s a millionth of a micrometer or a trillionth of a meter. Maybe it is easier to say there are one trillion waves per meter

1 trillion waves per meter          (where gamma waves begin)
100 billion waves per meter.     Gamma Rays/ X-Rays
10 billion waves per meter        XRays
1 billion waves per meter           X-Rays
1 billion waves per meter           X-Rays/Ultraviolet
100 million waves per meter     Ultraviolet
10 million wave per meter         Ultraviolet and Visible Spectrum
1 million waves per meter          Near infrared
100,000 waves per meter          Thermal Infrared   waves are 1/100 – 1/10 millimeter long
10,000 waves per meter           Thermal Infrared     waves are 1/10 – 1 millimeter long
1,000 waves per meter              Microwave               waves are 1 -10 millimeters long
100 waves per meter                  Microwave               waves are 1 -10 centimeters long
10 waves per meter                    Radio/TV                 waves are 10 centimeters – 1 meter long
1 wave per meter                         Radio/TV                 the waves are 1-10 meter long
1/10 wave per meter                  Radio/TV                 the waves are 10  to 100 meters long – .                                                                                           (These are very long waves)

It is an interesting exercise to use what you know or can learn about the metric system and of positive and negative powers of ten to calculate something like this.

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