How to Power a Lightbulb
– without Connecting it to Electricity?

In a series of experiments he conducted on August 29 and 30, 1831, scientist Michael Faraday discovered that moving a magnet near an electric wire (or any electrical conductor), creates electrical voltage in the wire. The impact of that discovery – which formed the basis for the generation of most of the world’s electricity – persists to this day. Watch a video explaining that influential discovery:

Explanation

Michael Faraday was an exceptional scientist with a fascinating biography. He did not attend a university or even high school. Nevertheless, he is considered one of the greatest researchers of all time and reached that status through intense willpower and perseverance, which enabled him to realize his genius.

One of Faraday’s most important discoveries, called today Faraday’s Law, is the phenomenon known as electromagnetic induction. It is difficult to think of another discovery with such far-reaching effects on modern life, as it has made the use of electricity inside our homes possible.

In Faraday’s times (1791-1867), electricity could be produced only by primitive batteries or the rubbing of two materials together to generate static electricity. Both methods yielded relatively small amounts of electrical energy and there was no method to generate electricity on a large scale. Faraday conducted numerous experiments involving magnetism and electricity, and, 186 years ago this week, discovered that when he passed current through a coil of metal wire (an electrical conductor), voltage was created in another metal coil close by (here is a link to Faraday’s diary – a description of those pioneering experiments from August 29-30, 1831, appears on page 37.) Further experiments soon led to his discovery that just moving a magnet through a metal coil was enough to create voltage between the ends of the metal coil. In fact, a magnet is what gave rise to electricity in the first experiment – a magnetic field was created in the first coil when an electrical current was passed through it. Scientifically speaking, we can say that changes in the magnetic flux created an electromotive force (electricity) in the coil. (The law’s exact definition is: “The electromotive force around a closed path is equal to the negative of the time rate of change of the magnetic flux enclosed by the path.”)

That law conveys that on its own, a magnet will not generate electricity when in proximity to a coil made of electricity-conducting material; the magnet must be in continuous motion, i.e., there must be perpetual change in the magnetic field next to the conducting coil for electricity to be generated within it. The process is one of energy conversion, from kinetic/mechanical energy, that is, the magnet’s movement, into electrical energy. The magnet does not “run out” of magnetism; neither is it the source of the energy for the electricity generation process – it only makes it possible. Because magnets have orientation (they have two poles), the magnet’s movement in both opposing directions near the coil creates opposing changes in the magnetic flux and therefore, opposing electrical currents – as demonstrated in the video.

Faraday understood that the easiest way to create constant motion is by rotation, and that led him to invent the first dynamo / generator; the first device able to produce, steady, uninterrupted, continuous electrical current for as long as the magnet continued to rotate. In Faraday’s dynamo, it was the electrical conductor that rotated and the magnet was fixed in place.

Since Faraday’s initial discovery, the process has been improved a number of times. Eventually, the magnet was replaced by an electromagnet making powerful magnetic fields available, which means the production of a much more powerful electric current. However, the principle remains the same. Even today, electricity companies use that principle to generate most of the world’s electricity – mechanical rotation is converted into electricity.

The differences between power stations are usually in the method used to power the mechanical rotation – fossil fuel engines, coal-fired turbines, gas, nuclear power, hydro-electric, wind. But all those methods still employ magnetic fields rotating around metal wires to generate electricity. Today, only a tiny amount of electricity is generated using methods that do not use generators – solar panels, for example. 

To understand why and how electromagnetic induction actually functions, we can say in brief that it is simply the embodiment of one of nature’s laws regarding electricity and magnetism: Metals contain free electrons and electrons are very small particles carrying a negative electric charge. When electrons move relative to an electric field (or an electrical field moves relative to the electrons as shown in the demonstration), a force called the Lorentz Force acts on the electrons and pushes them in the direction perpendicular to their movement and the direction of the magnetic field. That force is expressed as the movement of electrons in an electric circuit – i.e., electric current.