If you've never used a Faraday flashlight, you're missing out on a fairly recent application of the unschooled genius of Michael Faraday. Faraday (1791—1867) was an English scientist who studied electromagnetism and electrochemistry and was completely self-taught. Being born the third of four children of a blacksmith just outside of London, England, he had no formal schooling beyond basic reading, writing, and math, and never went to college.
At the age of 14, he was apprenticed for seven years to bookbinder George Riebau. It was in this capacity that he discovered a love of science, as Riebau allowed him to read the books with which he worked. When his apprenticeship ended, a customer of Riebau's gave Faraday tickets to attend four lectures by Humphry Davy, the professor of chemistry at the Royal Institution. He attended and took copious notes. Faraday applied to Davy for a job, and included his notes. Davy was impressed, and a year later, when Faraday was 22, hired him to be his assistant for the next 18 months as Davy toured scientific institutions in Europe.
Humphry Davy contributed to Faraday's scientific education and introduced him to famous scientists in Europe, including André-Marie Ampère (for whom the ampere or amp is named) and Alessandro Volta (for whom the volt is named). When Davy retired in 1827, Faraday replaced him as professor of chemistry at the Royal Institution.
Although Faraday worked in chemistry and discovered benzene, his greatest discoveries involved electricity. He experimented with electromagnetism and found that moving a magnet through a loop of wire would electrify the wire. In 1821, he invented the electric motor, and in 1831 he made the first dynamo, known as the Faraday disc, a forerunner of today's electrical generator, when he discovered the induction of electric currents. Faraday's law of induction is the basic operating principle of transformers and many types of electrical motors and generators.
He discovered the "Faraday effect," the first evidence that light and electromagnetism are related. He also discovered electrolysis, the use of electricity to separate matter. In addition to the dynamo, he invented the "Faraday cage," a device that blocked electric waves.
His electromagnetic discoveries led to James Clerk Maxwell creating the first unified field theory in physics. Maxwell modeled Faraday's law in mathematical terms. Faraday's law became one of the four Maxwell equations, which in turn evolved into what became known as field theory.
Although Faraday himself had little formal education, he took it upon himself to educate the general public about science, and was known for his ability to explain things clearly. Humble and unassuming, he turned down the Presidency of the Royal Society and rejected a knighthood.
The farad, a unit of capacitance, is named in his honor, and in 2002, he was ranked number 22 in the BBC's list of the 100 Greatest Britons.
The Faraday flashlight, a fairly recent invention based on his work, is a flashlight for emergency situations that doesn't use batteries, which can be unreliable. When the flashlight is shaken (or cranked, for crank models), a magnet goes back and forth through a coil of wire, which creates an electrical current that is stored in a capacitor, which lights the bulb.
The Faraday flashlight is only a minor demonstration of this great scientist's genius when compared to the impact that his own inventions and discoveries have made on the world, but his legacy continues to live on, and his has become a household name.