What is transmitted by a radio wave?
Radio waves are used for wireless transmission of sound messages, or information, for communication, as well as for maritime and aircraft navigation. The information is imposed on the electromagnetic carrier wave as amplitude modulation (AM) or as frequency modulation (FM) or in digital form (pulse modulation).
Do radio waves cause health problems?
The WHO/International Agency for Research on Cancer (IARC) has classified radiofrequency electromagnetic fields as possibly carcinogenic to humans (Group 2B), based on an increased risk for glioma, a malignant type of brain cancer, associated with wireless phone use.
What is the main health effect associated with radiofrequency?
Exposure to very high RF intensities can result in heating of biological tissue and an increase in body temperature. Tissue damage in humans could occur during exposure to high RF levels because of the body’s inability to cope with or dissipate the excessive heat that could be generated.
Who was the first person to transmit radio waves?
Born in Bologna, Italy, in 1874 to an Italian father and an Irish mother, Marconi studied physics and became interested in the transmission of radio waves after learning of the experiments of the German physicist Heinrich Hertz.
How are radio waves used to study the heavens?
Radio telescopes look toward the heavens to view planets, comets, giant clouds of gas and dust, stars, and galaxies. By studying the radio waves originating from these sources, astronomers can learn about their composition, structure, and motion.
How did Heinrich Hertz prove the existence of radio waves?
They range from the length of a football to larger than our planet. Heinrich Hertz proved the existence of radio waves in the late 1880s. He used a spark gap attached to an induction coil and a separate spark gap on a receiving antenna.
When was speech first transmitted on a radio?
In 1915, speech was first transmitted by radio across the continent from New York City to San Francisco and across the Atlantic Ocean. Five years later, Westinghouse’s KDKA-Pittsburgh broadcasted the Harding-Cox election returns and began a daily schedule of radio programs.