X.

Michael Faraday

Born into poverty, Michael Faraday was unschooled but had a strong religious upbringing. Apprenticed to a bookbinder at the age of 14, he actually managed to read some of the books he bound. He thus educated himself while developing a manual dexterity that would serve him well as an experimenter. One day a client brought in a copy of the third edition of the Encyclopaedia Britannica to be rebound, including a volume with an article on electricity. Faraday read it and was hooked, and the world was never the same.

Over the next 50 years Faraday's discoveries literally electrified England and set in motion as radical a change in the way people live as has ever resulted from the inventions of one human being.

Faraday accomplished an amazing amount in the way of science and invention. Starting his professional life as a chemist at the age of 21, he discovered a number of organic compounds, including benzene. He made the transition to physics by thoroughly exploring the principles of electrochemistry. Faraday then went on to make major discoveries in the fields of electricity and magnetism. He was the first to produce an electric current from a magnetic field. He invented the electric motor and dynamo, demonstrated the relation between electricity and chemical bonding, and discovered the effect of magnetism on light. Faraday accomplished all this without a Ph.D., M.A., B.A., or high school equivalency degree. He was also mathematically illiterate. Faraday recorded his discoveries not in equations but in plain descriptive language, often accompanied by pictures based on his mental images, which helped him explain the data.

Faraday began his work in electrochemistry by systemizing the nomenclature. He called the metals immersed in the liquid electrodes. The negative electrode was a cathode, the positive an anode. When the electricity zipped through the water, it caused charged atoms to migrate through the liquid from cathode to anode. Normally, chemical atoms are neutral, having neither a positive nor a negative charge. But the electric current somehow charged the atoms. Faraday called these charged atoms ions. Scientists later learned that an ion is an atom that has become charged because it has lost or gained one or more electrons. Although the existence of electrons was unknown in Faraday’s time, some evidence suggests that he suspected their existence. In the 1830s he carried out a series of spectacular experiments that resulted in two simple summary statements known as Faraday’s laws of electrolysis:

What these laws mean is that electricity is not smooth and continuous but can be divided into “chunks.” Faraday’s laws tell us that atoms in the liquid (ions) migrate to the electrode, where each ion is presented with a particular quantity of electricity. The Faraday laws thus point to an unavoidable conclusion: There are particles of electricity. This conclusion, however, had to wait about 60 years to be dramatically confirmed by the discovery of the electron.

The route to the modern understanding of electricity is akin to a double play combination in baseball: in this case, Oersted to Ampere to Faraday. Oersted and Ampere made the first steps in understanding electric currents and magnetic fields. Electric currents flowing in wires, like those in your house, make magnetic fields. Thus you can make as powerful a magnet as you want, from the tiny battery-operated magnets that drive small fans to the giant ones used in particle accelerators, by organizing currents.

Faraday struggled for a long time to unify electricity and magnetism. If electricity can make magnetic fields, he wondered, can magnets make electricity? Indeed, why not, he reasoned, since nature loves symmetry? It took Faraday more than ten years, from 1820 to1831, to prove that the process was indeed possible, and it was arguably his greatest achievement. Faraday's experimental discovery is called electromagnetic induction, and the symmetry he sought emerged in a surprising form.

Faraday wondered whether a magnet could move a current-carrying wire. Visualizing the forces, he rigged up a device in which one end of a wire was connected to a battery and the other end hung in a beaker of mercury, a liquid conductor that helped the current flow. The electric wire hung free so it could revolve around an iron magnet in the beaker. When he turned the current on, the wire moved in a circle around the magnet. Faraday had converted electricity to motion with this invention, which we know today as an electric motor.

In another experiment, Faraday wrapped a large number of turns of copper wire on one side of a soft iron doughnut, and then connected the two ends of the coil to a sensitive current-measuring device called a galvanometer. He wrapped a similar length of wire on the other side of the doughnut, connecting these ends to a battery so that current could flow in the coil. (This device is now called a transformer.) Faraday now had two coils wound on opposite sides of a doughnut. One coil, call it coil A, is connected to a battery, while the other, coil B, is connected to a galvanometer. What happened when he turned on the juice?

The answer is important to the history of science. When the current flows in coil A, the electricity produces magnetism. Faraday reasoned that this magnetism should induce a current in coil B. But instead, he got a strange effect. When he turned on the current, the needle in the galvanometer connected to coil B deflected, but only momentarily. After the sudden jump, the needle remained pointed maddeningly to zero. When Faraday disconnected the battery, the needle deflected briefly in the opposite direction, then again pointed at zero. Increasing the sensitivity of the galvanometer had no effect. Increasing the number of turns in each coil still had no effect. Even using a much stronger battery had no effect. And then what scientists call the “Eureka” moment came: Faraday figured out that a changing current in the first coil had induced a current in the second, but only when the first current was actively turning on or off—that is, in the process of changing. As soon as the current—and the surrounding magnetic field—became stable, the field stopped inducing a change in the second coil. As Faraday suspected, and as the next 30 years or so of research would demonstrate, a changing magnetic field generates an electric field.

The technology that eventually emerged from this discovery was the electric generator. By rotating a magnet mechanically, it is possible to produce a constantly changing magnetic field, which will generate an electric field and, if connected to a circuit, an electric current. One can rotate a magnet by turning a crank, by using the force of a waterfall, or by harnessing a steam turbine. Now humankind had a potential way to generate electricity and turn night into day.

Faraday built the first hand-cranked electrical generator, which in those days was called a dynamo. But he was too involved in the process of experimenting and making new discoveries to figure out what to do with it. The story is often told that the British prime minister visited Faraday's laboratory in 1832 and, pointing to the funny machine, asked what use it had. 'I know not, but I wager that one day your government will tax it,' said Faraday. Sure enough, a tax on electrical generation was levied in England in 1880.