Explanation:
Chemical compound, any substance composed of identical molecules consisting of atoms of two or more chemical elements. ... The fundamental principle of the science of chemistry is that the atoms of different elements can combine with one another to form chemical compounds.
Telephones began as large, clunky devices capable of transmitting and receiving voice messages over short distances, then evolved to lighter, transportable cellular devices capable of enabling communications over large distances. In the United States, Alexander Graham Bell receives credit for producing the first telephone in 1876. Bell established a basic system of communications allowing people to talk with each other remotely over short distances through receivers. <span>As with other technologies, phone technologies improved dramatically and rapidly following Bell's introduction of the telephone to American life. In addition to improvements in the device itself, transmissions methods improved as well. By 1900, telephone companies established communication lines through many American cities, allowing people to connect over larger distances. These lines contained special coils to reduce static and expedite transmissions. Telephone calls remained limited to local regions within the borders of the United States through 1915. Then, Alexander Graham Bell completed the first transcontinental call with Thomas Watson. Rotary phones emerged just before 1920, and a numbering plan arrived in the late 1940s to allow fast and direct connections between callers. In 1956, telephone cables permitted transcontinental calls for the first time. In the 1960s and 1970s, phone use extended to emergency service and the military. Portable phones arrived in the early 1970s; by 2000, thousands of Americans carried lightweight, compact phones wherever they went. AND THEY HAVE IPHONES NOW XDD
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1. Planetary Winds:
The winds blowing throughout the year from one latitude to another in response to latitudinal differences in air pressure are called “planetary or prevailing winds”. They involve large areas of the globe.
4. Periodic Winds:
Periodic winds change their direction periodically with the change in season, e.g., Monsoons, Land and Sea Breezes, Mountain and Valley Breezes.
