The relationship between electricity and magnetism was long suspected, if not fully understood. William Gilbert, who experimented with electricity in the early seventeenth century, was motivated to do so by a desire to improve maritime navigation using magnetic compasses. Many of Benjamin Franklin’s experiments were aimed at better understanding the relationship between electricity and magnetism. The most significant advances in understanding this relationship, however, came in the 1800s, starting with Danish scientist Hans Christian Ørsted. In 1820, Ørsted discovered (quite by accident) that an electric wire would cause the needle of a compass to move. Ørsted correctly theorized that electricity created a magnetic field, an observation that was built upon by other scientists who endeavored to use electricity to create magnets. The staggering potential of this discovery was only uncovered, however, when scientists reversed the process: rather than using electricity to create magnets, they sought to use magnets to generate electricity. This discovery was made in the early 1830s by two scientists working independently on opposite sides of the Atlantic Ocean—Michael Faraday in Great Britain and Joseph Henry in the United States. These two men discovered the principle of electromagnetic induction: an electric current could be generated by exposing a conductor (such as a metal wire) to a constantly changing magnetic field. Because Faraday published his findings first, he is generally credited with making
this discovery, though Henry likely made his discovery at around the same time.
The discovery of electromagnetic induction opened up a wide range of possible applications for electricity. It was now possible to generate steady currents of electricity rather than just short bursts, and advances in battery technology allowed for much more efficient and long-term storage of electricity. The first field that saw a major change was communication, with the invention of the electric telegraph. The earliest commercial telegraphs used the flow of electric current to move a series of needles on a receiver that would point to letters or coded symbols that represented words or simple instructions. The system, while impressive, was cumbersome, requiring multiple wires and needles to convey the information. The breakthrough in electronic communication came in 1844 with Samuel Morse’s invention of an alphabetic code represented by a series of short or long clicks caused by the flow or interruption of an electric current to a telegraph machine. The system was ingenious in its simplicity: it was efficient, very easy to teach to operators, and required only one telegraph line. Later in the nineteenth and into the early twentieth centuries, scientists’ understanding of electromagnetism was further refined, leading to the eventual invention of the wireless telegraph and the radio. The discovery of electromagnetism, then, completely revolutionized human communication.