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The Constellations

The random arrangement of the stars visible to the naked eye has remained essentially unchanged since the time of the first written records. One of the earliest complete lists we have was compiled in about 120 BC by the Greek astronomer Hipparchus, and all the stars that he described can be found, with the same brightness and in practically the ...

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TheConstellations
Astronomy

Big Fish

The phrase 'big fish eat little fish' may hold true when it comes to planets and stars. Perhaps as many as 100 million of the sun-like stars in our galaxy harbor close-orbiting gas giant planets like ... Continue reading

BigFish
Science

Inventor: George Washington Carver

George Washington Carver, born a slave in 1864 (approximately), contributed significantly to agricultural research. Although he was orphaned as an infant, endured hardship in pursuit of his education, ... Continue reading

GeorgeWashingtonCarver
Astronomy

Two Face? Absolutely!

During the Viking missions to Mars in the mid 1970s, the planet was imaged from orbit by the Viking 1 and 2 Orbiters. These spacecraft returned images of regions of the planet that, while similar to ... Continue reading

TwoFaceAbsolutely
Geology

Under The Crust

Three centuries ago, the English scientist Isaac Newton calculated, from his studies of planets and the force of gravity, that the average density of the Earth is twice that of surface rocks and ... Continue reading

UnderTheCrust

What Is Radiofrequency Energy (Rf)?

WhatIsRadiofrequencyEnergyRadiofrequency (RF) energy is another name for radio waves. It is one form of electromagnetic energy that makes up the electromagnetic spectrum. Some of the other forms of energy in the electromagnetic spectrum are gamma rays, x-rays and light. Electromagnetic energy (or electromagnetic radiation) consists of waves of electric and magnetic energy moving together (radiating) through space. The area where these waves are found is called an electromagnetic field. Radio waves are created due to the movement of electrical charges in antennas. As they are created, these waves radiate away from the antenna. All electromagnetic waves travel at the speed of light. The major differences between the different types of waves are the distances covered by one cycle of the wave and the number of waves that pass a certain point during a set time period.

The wavelength is the distance covered by one cycle of a wave. The frequency is the number of waves passing a given point in one second. For any electromagnetic wave, the wavelength multiplied by the frequency equals the speed of light. The frequency of an RF signal is usually expressed in units called hertz (Hz). One Hz equals one wave per second. One kilohertz (kHz) equals one thousand waves per second, one megahertz (MHz) equals one million waves per second, and one gigahertz (GHz) equals one billion waves per second. RF energy includes waves with frequencies ranging from about 3000 waves per second (3 kHz) to 300 billion waves per second (300 GHz). Microwaves are a subset of radio waves that have frequencies ranging from around 300 million waves per second (300 MHz) to three billion waves per second (3 GHz).

Probably the most important use of RF energy is for telecommunications. Radio and TV broadcasting, wireless phones, pagers, cordless phones, police and fire department radios, point-to-point links and satellite communications all rely on RF energy. Other uses of RF energy include microwave ovens, radar, industrial heaters and sealers, and medical treatments. RF energy, especially at microwave frequencies, can heat water. Since most food has a high water content, microwaves can cook food quickly. Radar relies on RF energy to track cars and airplanes as well as for military applications. Industrial heaters and sealers use RF energy to mold plastic materials, glue wood products, seal leather items such as shoes and pocketbooks, and process food. Medical uses of RF energy include pacemaker monitoring and programming.