ELECTROMAGNETISM

History
-The history of electromagnetic theory begins with ancient measures to deal with atmospheric electricity, in particular lightning. People then had little understanding of electricity, and were unable to scientifically explain the phenomena. In the 19th century there was a unification of the history of electric theory with the history of magnetic theory... Continuation ->

Continuation
It became clear that electricity should be treated jointly with magnetism, because wherever electricity is in motion, magnetism is also present. Magnetism was not fully explained until the idea of magnetic induction was developed. Electricity was not fully explained until the idea of electric charge was developed.

SIGNIFICANT PERSONS

• Edmund Halleys
• Hans Christian Oerested

Edmund Halleys Theory
How can an iron magnet produce such changes? Edmond Halley (of comet fame) ingeniously proposed that the Earth contained a number of spherical shells, one inside the other, each magnetized differently, each slowly rotating in relation to the others.

Hans Oerested Experiments
-He planned to demonstrate the heating of a wire by an electric current, and also to carry out demonstrations of magnetism, for which he provided a compass needle mounted on a wooden stand... Continuation->

Continuation
-While performing his electric demonstration, he noted to his surprise that every time the electric current was switched on, the compass needle moved.

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