Who invented the principles of the magnetic effect of electricity

He carried out an experiment that is to this day familiar in any science classroom in the world. He replaced the wire helix connected to the battery, and which was generating a magnetic field, with a simple permanent bar magnet. He next took a hollow coil of wire the ends of which he connected to a galvanometer.

By thrusting the magnet quickly into the coil and saw the galvanometer needle deflect. Reversing the process by pulling the magnet out caused the needle to deflect in the opposite direction.

Then, by constantly moving the bar magnet in and out of the coil he could make the galvanometer needle vibrate from side to side in phase with the motion of the magnet. Faraday went on to experiment with more powerful permanent magnets and electromagnets of different strengths, but the basic principle was the same.

But at this point he admits that he has yet to understand the properties of matter whilst retained in this state, particularly since he experiments with various different conducting materials, such as copper and silver, which are not themselves magnetic. Faraday realized he needed to find a way of producing a changing magnetic field and went on to design an improved version of Arago's disc experiment. He mounted a copper disc on a brass axes so that it could freely rotate between two poles of a permanent magnet.

He then connected the disc to a galvanometer by attaching one wire to its centre and another touching its rim as in figure 2. Faraday's spinning disc—generating a continuous electric current in a conducting disc as it spins between two poles of a powerful permanent magnet. This diagram is from Faraday's original paper [ 9 ].

Copyright The Royal Society. Then, when the disc was rotated, the galvanometer registered a continuous current that clearly had to be travelling in a radial direction through the disc. Reversing the direction of spin of the disc caused the galvanometer needle to be deflected in the opposite direction implying a reversal in direction of the electric current. With this experiment, Faraday was able to show how a magnetic field and continuous mechanical motion would produce a continuous electric current.

He had invented the electric generator. He then goes on to attach the two wires that connected to the galvanometer to different points on the rim of the spinning disc and realizes that the induced current is always at right angles to the motion of the disc and that in this case the flow of electricity is in a radial direction.

Of course we can see how far away Faraday, and others, were at this time from understanding the true nature of electric current by the way he still refers to the different kinds of electricity. He defines five distinct types: Voltaic-Electricity as produced by a battery , Common-Electricity such as the discharge from a charged body like a Leyden jar , Magneto-Electricity by which he means an induced current , Thermo-Electricity and Animal-Electricity such as was known to be produced by some creatures such as the electric eel.

It should be mentioned at this point that the American scientist, Joseph Henry — , whose life, starting from poor and humble beginnings, in many ways mirrored that of Michael Faraday, was also working independently on electro-magnetism on the other side of the Atlantic — although interest in the subject was certainly circulating across the Atlantic by the s. Importantly, it is worth stating that Henry in fact beat Faraday to the discovery of inductance by a few months in , but it was Faraday who published first and, despite the delays that so frustrated him, is therefore credited with the discovery.

Today, every schoolboy and schoolgirl learns about Fleming's left- and right-hand rules. These useful visual mnemonics were developed by the English engineer, John Ambrose Fleming — in the late nineteenth century and give a simple way of working out the direction of motion in an electric motor the left-hand rule and the direction of current in a generator the right-hand rule.

For example, in the left hand rule, the index finger, middle finger and thumb can be held pointing in three mutually orthogonal directions to represent the magnetic F ield F irst finger , electric Current se C ond finger and the thrust, or Motion, thu M b. In reading Faraday's paper, one is struck by just how simple these mnemonics are and how useful they would have been had he known about them.

But Faraday had got it the wrong way round [ 10 ]. Figure 3 shows an extract from his diary his laboratory notebook written on 26 March , which was just a few days before his paper appeared in print and therefore too late for him to make any changes to it.

We even see an interesting first attempt at drawing a diagram. The one below it depicts the correct mutual orthogonality of electricity, magnetism and motion and is regarded as one of the most significant drawings in his notebook.

Then if electricity be determined in one line and motion in another, magnetism will be developed in the third; or if electricity be determined in one line and magnetism in another, motion will occur in the third. Or if magnetism be determined first then motion will produce electricity or electricity motion. Reproduced by courtesy of the Royal Institution of Great Britain. There is no doubt that the experiments described in Faraday's paper not only laid the foundations for truly understanding the nature of electricity, but for its practical application in ways that would transform our world.

Within months, many inventors became interested in these wondrous potential applications, and yet many of them did not understand, or even care, about the physics behind electromagnetic induction.

Indeed, a true mathematical theory would not emerge until the work of James Clerk Maxwell in The applications of Faraday's discoveries quickly became apparent as other scientists, engineers and inventors began to work on the construction of evermore-sophisticated electric generators that could be put to practical use [ 11 ].

For example, the French instrument maker, Hippolyte Pixii — , built a crude electric generator as early as , based directly on Faraday's ideas of induction. The device consisted of a hand operated spinning magnet above a coil with an iron core inside. A current pulse in the coil was produced each time one of the two poles of the magnet passed over it.

However, what was being produced was an alternating AC current as the direction of the induced current changed with each half turn of the magnet. As there was no real use for AC currents at this time its advantages would only become apparent later a means had to be found to convert this into a direct DC current.

Soon after Pixii's invention, others began to produce their own similar devices. By the mids, such machines were producing a range of different effects of induced electric currents, from chemical decompositions to sparks, all by turning a handle that rotated a magnet.

The first important practical application of Faraday's discovery, however, was not the electric generator but the telegraph. Based on the ability to control a magnet at a distance, this invention allowed the possibility of long distance communication that would connect the world. And it was based on a very simple idea: the movement of a conducting coil over a magnet in one location induces a current that is transmitted to another location where it affects a galvanometer.

The idea was implemented almost as soon as the world learnt of Faraday's work, particularly by Pavel Schilling, Carl Friedrich Gauss and Wilhelm Weber. A commercial, large-scale application of Faraday's discovery was made by the electroplaters of Birmingham as early as There, at least two companies made use of his method of extracting electricity from magnetism on a large scale [ 12 ].

But these early generators were incredibly cumbersome and of course required a source of power to produce the mechanical motion in the first place. The first experimental deployment of a magneto-electric machine powered by a steam engine took place in a British lighthouse. The device, which weighed 2 tons, was invented by the Englishman Frederick H.

The motor features a stiff wire which hangs down into a glass vessel which has a bar magnet secured at the bottom. The glass vessel would then be part filled with mercury a metal that is liquid at room temperature and an excellent conductor.

Faraday connected his apparatus to a battery, which sent electricity through the wire creating a magnetic field around it. This field interacted with the field around the magnet and caused the wire to rotate clockwise. This discovery led Faraday to contemplate the nature of electricity. Unlike his contemporaries, he was not convinced that electricity was a material fluid that flowed through wires like water through a pipe.

Instead, he thought of it as a vibration or force that was somehow transmitted as the result of tensions created in the conductor. Find out more here Close. The geomagnetic field generated will be dipolar in character, similar to the magnetic field in a conventional magnet, with lines of magnetic force lying in approximate planes passing through the geomagnetic axis.

The principle of the compass needle used by the ancient mariners involves the alignment of a magnetized needle along the Earth's magnetic axis with the imaginary south pole of the needle pointing towards the magnetic north pole of the Earth.

The magnetic north pole of the Earth is inclined at an angle of 11 degrees away from its geographical north pole. Five basic types of magnetism have been observed and classified on the basis of the magnetic behavior of materials in response to magnetic fields at different temperatures. These types of magnetism are: ferromagnetism, ferrimagnetism, antiferromagnetism, paramagnetism, and diamagnetism. Ferromagnetism and ferrimagnetism occur when the magnetic moments in a magnetic material line up spontaneously at a temperature below the so-called Curie temperature, to produce net magnetization.

The magnetic moments are aligned at random at temperatures above the Curie point, but become ordered, typically in a vertical or, in special cases, in a spiral helical array, below this temperature. In a ferromagnet magnetic moments of equal magnitude arrange themselves in parallel to each other.

In a ferrimagnet, on the other hand, the moments are unequal in magnitude and order in an antiparallel arrangement. When the moments are equal in magnitude and ordering occurs at a temperature called the Neel temperature in an antiparallel array to give no net magnetization, the phenomenon is referred to as antiferromagnetism. These transitions from disorder to order represent classic examples of phase transitions. The magnetic moments-referred to as spins-are localized on the tiny electronic magnets within the atoms of the solid.

Mathematically, the electronic spins are equal to the angular momentum the rotational velocity times the moment of inertia of the rotating electrons.

The spins in a ferromagnetic or a ferrimagnetic single crystal undergo spontaneous alignment to form a macroscopic large scale magnetized object. Most magnetic solids, however, are not single crystals, but consist of single crystal domains separated by domain walls. The spins align within a domain below the Curie temperature, independently of any external magnetic field, but the domains have to be aligned in a magnetic field in order to produce a macroscopic magnetized object.

This process is effected by the rotation of the direction of the spins in the domain wall under the influence of the magnetic field, resulting in a displacement of the wall and the eventual creation of a single large domain with the same spin orientation.

Paramagnetism is a weak form of magnetism observed in substances which display a positive response to an applied magnetic field. This response is described by its magnetic susceptibility per unit volume, which is a dimensionless quantity defined by the ratio of the magnetic moment to the magnetic field intensity.

Paramagnetism is observed, for example, in atoms and molecules with an odd number of electrons, since here the net magnetic moment cannot be zero. Diamagnetism is associated with materials that have a negative magnetic susceptibility.

It occurs in nonmagnetic substances like graphite, copper, silver and gold, and in the superconducting state of certain elemental and compound metals. The negative magnetic susceptibility in these materials is the result of a current induced in the electron orbits of the atoms by the applied magnetic field. The electron current then induces a magnetic moment of opposite sign to that of the applied field. The net result of these interactions is that the material is shielded from penetration by the applied magnetic field.

The magnetic field or flux density is measured in metric units of a gauss G and the corresponding international system unit of a tesla T. The Swedish astronomer, however, also is notable as the first person to make a connection between the radiant atmospheric phenomenon known as the aurora borealis , or the northern lights, and the magnetic field of the Earth.

He published his studies of the aurora borealis, including his accurate speculation regarding its relation to magnetism, in Termed the BCS theory , it is heavily based on a phenomenon known as Cooper pairing. According to the theory, the electrons in a superconducting material form associated pairs that together act as a single system. Unless the movement of all pairs is halted simultaneously, the current flowing through a superconductor meets no resistance, and will continue ad infinitum.

Charles-Augustin de Coulomb — Charles-Augustin de Coulomb invented a device, dubbed the torsion balance , that allowed him to measure very small charges and experimentally estimate the force of attraction or repulsion between two charged bodies. William Crookes — English scientist William Crookes was very innovative in his investigations with vacuum tubes and designed a variety of different types to be used in his experimental work. Crookes tubes are glass vacuum chambers that contain a positive electrode anode and a negative electrode cathode.

When an electrical current is passed between the electrodes of one of the tubes, a glow can be seen in the chamber. Crookes also discovered the element Thallium. Humphry Davy — Humphry Davy was a pioneer in the field of electrochemistry who used electrolysis to isolate many elements from the compounds in which they occur naturally. Electrolysis is the process by which an electrolyte is altered or decomposed via the application of an electric current. In addition to his isolation of sodium, potassium and other alkaline earth metals, electrolysis enabled Davy to disprove the view proposed by French chemist Antoine-Laurent Lavoisier that oxygen was an essential component of all acids.

Peter Debye — Peter Debye carried out pioneering studies of molecular dipole moments, formulated theories of magnetic cooling and of electrolytic dissociation, and developed an X-ray diffraction technique for use with powdered, rather than crystallized, substances. For his work with dipole moments, the vector quantities related to the distribution of electric charges are measured in debyes. Also, in recognition of a number of his scientific contributions, Debye received the Nobel Prize in Chemistry in He received more than patents over the course of his lifetime, the most important of which was for a three-electrode vacuum tube , or triode, that he called the Audion.

The invention of the Audion, a device capable of amplifying and modulating electromagnetic signals that could also function as an oscillator, was a crucial step in the early electronics industry.

Until the invention of the transistor in , the triode was featured in almost all electronic equipment. Paul A. Dirac — Paul Adrien Maurice Dirac was an outstanding twentieth century theoretical physicist whose work was fundamental to the development of quantum mechanics and quantum electrodynamics. Willem Einthoven — Willem Einthoven invented a string galvanometer that could be used to directly record the electrical activity of the heart.

The investigations he carried out with the device enabled him to determine that graphical recordings of heart activity, or electrocardiograms as they came to be known, generally conform to a basic type, that individuals produce their own characteristic electrocardiograms typically conforming to this type, and that deviations are often associated with heart disease.

For his discovery of the mechanism of the electrocardiogram, Einthoven was awarded the Nobel Prize in Physiology or Medicine in Enrico Fermi — Enrico Fermi was a titan of twentieth-century physics. Adept in both theory and experiment, the Italian-born American outlined the statistical laws that govern the behavior of particles that abide by the Pauli exclusion principle and developed a theoretical model of the atom when he was only in his mid-twenties.

These latter discoveries paved the way for invention of nuclear reactors and the atomic bomb. Richard Feynman — Theoretical physicist Richard Phillips Feynman greatly simplified the way in which the interactions of particles could be described through his introduction of the diagrams that now bear his name Feynman diagrams and was a co-recipient of the Nobel Prize in Physics in for his reworking of quantum electrodynamics QED.

He is often remembered as much for his offbeat personality and lively wit as for his considerable contributions to twentieth-century physics. John Ambrose Fleming — John Ambrose Fleming was an electronics pioneer who invented the oscillation valve , or vacuum tube, a device that would help make radios, televisions, telephones and even early electronic computers possible.

A brilliant innovator, Fleming was particularly adept at solving technical problems, and at various times in his life he was closely acquainted with James Clerk Maxwell, Thomas Edison and Guglielmo Marconi. He taught at University College, London, for many years and is often credited with devising the right-hand rule to help his students easily determine the directional relationships between a current, its magnetic field and electromotive force.

Luigi Galvani — Luigi Galvani was a pioneer in the field of electrophysiology, the branch of science concerned with electrical phenomena in the body. His experiments with dissected frogs and electrical charges led him to suggest the existence of a previously unknown type of electricity, which he dubbed animal electricity. Carl Friedrich Gauss — Although he is best known as one of the greatest mathematicians of all time, Carl Friedrich Gauss was also a pioneer in the study of magnetism and electricity.

To facilitate an extensive survey of terrestrial magnetism, he invented an early type of magnetometer , which is a device capable of measuring the direction and strength of a magnetic field. Gauss also developed a consistent system of magnetic units and with Wilhelm Weber built one of the first electromagnetic telegraphs.

Murray Gell-Mann Present — Murray Gell-Mann is a theoretical physicist who won the Nobel Prize for Physics in for his contributions to elementary particle physics. He is particularly well known for his role in bringing organization into the world of subatomic particles, which before his work seemed to be verging on chaos, and for developing the concept of quarks.