"I happen to have discovered a direct relation between magnetism and light, also electricity and light, and the field it opens is so large and I think rich." -Michael Faraday
Michael Faraday was an English chemist and physicist whose experiments in the 1800s laid the foundation in the fields of electricity, magnetism, and electrochemistry.
Born in 1791 to a blacksmith, Faraday’s family was too poor to afford much schooling for him. Fortunately, he was apprenticed to a bookbinder and therefore had plenty of opportunity to educate himself. As a young man, he began attending lectures given by noted chemist Humphry Davy. Davy was so impressed by Faraday’s aptitude that he gave him a job as his personal secretary. When Davy toured the scientific institutions of Europe, Davy went along on the extensive journey, employed as Davy’s valet. In spite of his irritation at being treated as a second class servant, Faraday had plenty of opportunity to soak up the latest advances in science.
Following the trip, Davy employed Faraday as his laboratory assistant. From there, Faraday’s career careened upward as he continuously made important discoveries in chemistry and physics. Eventually he was granted a lifetime appointment as professor of chemistry at the Royal Institution of Great Britain. Today he is credited as being one of the most influential scientists in history. It was largely due to his efforts that electricity became a viable technology.
One of Faraday’s most momentous discoveries concerned the construction of the electric dynamo. The dynamo he developed consisted of a copper disk rotating between the poles of a magnet. This became the precursor to modern-day power generators and electric motors, and acted as the springboard for a vast array of electrical machinery in industry. Faraday subsequently found that a conductor carrying DC electric current would generate a magnetic field, establishing the concept of the electromagnetic field in physics.
In 1836, Faraday demonstrated that an electrical charge will reside on the exterior of an electrical conductor, but the electricity will not be carried to anything on the interior side of that conductor. In other words, he showed that electricity travels around the surface of a conducting material, but will not go through that material. To prove this, Faraday electrified an empty pewter ice bucket, showing that the electricity was confined to the surface of the metal bucket, while there was no electricity present inside the ice bucket. Next, he built a room which he coated with metal foil. Using an electrostatic generator, he allowed high-voltage discharges to strike the outside of the room. His instruments showed that despite the high currents passing through the foiled walls, there was no electricity present inside the room. This basic construct became known as a Faraday cage, and it impacts our lives in many ways today.
Airplanes can safely fly through the middle of thunderstorms without fear of being struck by lightning, because the metal skin of the aircraft acts as a Faraday cage, protecting everything inside. An automobile acts the same way in a storm. In a microwave oven, the microwaves are trapped inside while the metal shell of the oven acts as a Faraday cage, preventing the microwaves from leaking out. The coaxial cables that plug into TVs and other electronic equipment are wrapped in a thin metal mesh that acts as a Faraday cage, preventing the radio frequency signal from leaking out while also preventing stray electric energy from leaking in, which would interfere with reception. An MRI machine in a hospital is also protected by a Faraday cage in order to shield the magnetic picture from interference from outside electrical influences. Some electrical linemen wear mesh Faraday cages very similar to chain mail in order to protect them from accidental electrocution.
An excellent Faraday cage !
Making a Faraday cage is a simple Saturday afternoon project that you can accomplish using materials found around the house or purchased for a few dollars. Here are instructions for building one using lumber and wire mesh. Yes, mesh will work just fine; it’s called a Faraday cage, not a Faraday box. Boxes and mesh work equally well, provided the mesh is small enough.
If you'd like to see step-by-step instructions on how I make my own Faraday cages, proceed to this page.