Radio: A Form Of Communication

Part I of Essay
Mr. Zambizi Physics Radio is a form of communication in which intelligence is transmitted without wires from one point to another by means of electromagnetic waves. Early forms of communication over great distances were the telephone and the telegraph. They required wires ....

Part II of Essay
.... Joseph Henry. They had individually developed the theory that a current flowing in one wire could induce (produce) a current in another wire that was not physically connected to the first. Hans Christian Oersted had shown in 1820 that a current flowing in a wire sets up a magnetic field around the wire. If the current is made to change and, in particular, made to alternate (flow back and forth), the building up and collapsing of the associated magnetic field induces a current in another conductor placed in this changing magnetic field. Thi ....