ScienceIQ.com

Flipping Magnetic Fields

North and south. We take these directions for granted. Pull out a compass and the needle will swing to the north in response to the magnetism in the Earth's crust. The magnetic poles roughly coincide with the axis of the Earth's rotation. But some scientists believe that the Earth's magnetic field has reversed itself several times within geological ...

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FlippingMagneticFields
Medicine

What Is High Blood Pressure?

High blood pressure is a blood pressure reading of 140/90 mmHg or higher. Both numbers are important. About one in every four American adults has high blood pressure. Once high blood pressure ... Continue reading

WhatIsHighBloodPressure
Medicine

My Aching Back

The back is an intricate structure of bones, muscles, and other tissues that form the posterior part of the body’s trunk, from the neck to the pelvis. The centerpiece is the spinal column, which not ... Continue reading

MyAchingBack
Engineering

Airbags

An automobile airbag is a safety device: its sole purpose is to prevent an occupant of the vehicle from impacting with the surrounding structure. Typically, in a collision, Newton's laws of motion ... Continue reading

Airbags
Astronomy

Reading The Colors of the Spectrum

Did you ever wonder how scientists can tell us so much about distant stars, for example, the surface temperature or chemical makeup of a star, light years away from Earth? Scientists can only use what ... Continue reading

SpectrumColors

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.