#electromagnetism
Copper isn’t magnetic but creates resistance in the presence of a strong magnetic field
Michael Faraday achieved electromagnetic induction here at the Ri for the first time #OnThisDay in 1831
His work revolutionised our understanding of electricity and led to the development of electric generators, motors, inductors & transformers ⚡️
Electromagnetic induction is the production of an electromotive force (voltage) across an electrical conductor in a changing magnetic field.
You can find his electromagnetic induction ring and notes within our Museum and archival collection!
If beautifully scrawling handwriting ain’t your thing, read the transcription of Faraday’s notes here.
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four-coil armature by Henry Metcalf Hobart and A. G. Ellis
three-phase armature winding by Henry Metcalf Hobart and A. G. Ellis
Red sprites over Puerto Rico above Hurricane Matthew, October 1, 2016, (and in September 2016) photos by Frankie Lucena. Read more: smithsonian.com,rapt in awe.
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It would take another two hundred years for the next big breakthrough, which came from the study of electricityandmagnetism.
The ancients had known that magnetism could be tamed; the invention of the compass by the Chinese harnessed the power of magnetism and helped launch an age of discovery. But the ancients feared the power of electricity. Lightning bolts were thought to express the anger of the gods.
The man who finally laid the foundation for this field was Michael Faraday, a poor but industrious youth who lacked any formal education. As a child, he managed to get a job working as an assistant at the Royal Institution in London. Normally, someone of his low social standing would forever sweep the floor, wash bottles, and hide in the shadows. But this young man was so tireless and inquisitive that his supervisors allowed him to perform experiments.
Faraday would go on to make some of the greatest discoveries in electricity and magnetism.
- He showed that if you take a magnet and move it inside a hoop of wire, then electricity is generated in the wire.
- One could also show the reverse, that a moving electric field can create a magnetic one.
- This was an amazing and important observation, since the relationship between electricity and magnetism was then totally unknown.
It gradually dawned on Faraday that these two phenomena were actually two sides of the same coin. This simple observation would help to open up the electric age.
He also invented the concept of a field, one of the most important concepts in all of physics.
- A field consists of these lines of force spread throughout space. Magnetic lines surround every magnet, and the magnetic field of the Earth emanates from the north pole, spreads through space, and then returns to the south pole.
- Even Newton’s theory of gravity can be expressed in terms of fields, so that the Earth moves around the sun because it moves in the sun’s gravitational field.
Faraday’s discovery helped to explain the origin of the magnetic field surrounding the Earth.
- Since the Earth spins, the electric charges inside the Earth also spin.
- This constant motion moving inside the Earth is responsible for the magnetic field. (But this still left open a mystery: Where does the magnetic field of a bar magnet come from, since there is nothing moving or spinning in it? We will return to this mystery later.)
Today, all the known forces of the universe are expressed in the language of fields first introduced by Faraday.
The God Equation: The Quest for a Theory of Everything by Michio Kaku
