Magnetism can generate electricity! Why don’t people use the Earth’s own large magnetic field to generate electricity?
Magnetism can generate electricity, which is a major law known to all. But why can’t people use the earth’s own magnetic field to generate electricity? This got people thinking. This requires first understanding electricity and magnetism.
Electricity and magnetism are separate but interrelated phenomena, related to the electromagnetic force. Together, they form the basis of electromagnetism, an important discipline of physics. In addition to the behavior caused by gravity, almost everything that happens in our daily life is due to the electromagnetic force. It is responsible for the interactions between atoms and the flow between matter and energy. The other fundamental forces are the weak and strong nuclear forces, which govern radioactive decay and the formation of atomic nuclei. Since electricity and magnetism are so important, it’s a good idea to start with a basic understanding of what they are and how they work.
Electricity is a phenomenon associated with charges at rest or in motion. The source of charge can be an elementary particle, an electron that is negatively charged, a proton that is positively charged, an ion, or any larger object that has an imbalance of positive and negative charges. Positive and negative charges attract each other, while like charges repel each other. Familiar examples of electricity include lightning, electrical current from an electrical outlet or battery, and static electricity. Common SI units of electricity include amperes for current, coulombs for charge, volts for potential difference, ohms for resistance, and watts. A point charge at rest has an electric field, but if the charge is in motion it also produces a magnetic field.
Magnetism is defined as the physical phenomenon of moving electric charges. In addition, a magnetic field can induce the movement of charged particles, creating an electric current. Electromagnetic waves have both electrical and magnetic components. The two components of the wave move in the same direction, but at right angles to each other. Like electricity, magnetism creates attraction and repulsion between objects. While electricity is based on positive and negative charges, there are no known magnetic monopoles. Any magnetic particle or object has a “North” pole and a “South” pole, the direction of which depends on the direction of the Earth’s magnetic field. Magnet-like poles repel each other, for example, north poles repel north poles, while opposite poles attract each other. Common examples of magnetism include the response of a guide to the Earth’s magnetic field, the attraction and repulsion of a bar magnet, and the magnetic field around an electromagnet.
However, every moving charge has a magnetic field, so the orbiting electrons of atoms create a magnetic field; there is a magnetic field associated with the lines of force; and hard disks and speakers rely on magnetic fields to work. Key SI units of magnetism include Tesla for magnetic flux density, Weber for magnetic flux, amperes per meter for magnetic field strength, and Henry for inductance.
The word electromagnetism is a combination of the Greek words elektron and magnetis lithos. The ancient Greeks were familiar with electricity and magnetism, but considered them to be two different phenomena. This relationship, known as electromagnetism, wasn’t described until James Clerk Maxwell published a treatise on electricity and magnetism in 1873. Maxwell’s work included 20 well-known equations, which were later condensed into 4 partial differential equations.
The basic concept represented by the equation is as follows: the same kind of charges repel each other, and the different kinds of charges attract each other. Attraction or repulsion is inversely proportional to the square of the distance between them. Magnetic poles always exist in a north-south pair. Like poles repel, opposite poles attract. The current in the wire creates a magnetic field around the wire. The direction of the magnetic field depends on the direction of the current. This is the “right hand rule”, if your thumb points in the direction of the current, the direction of the magnetic field will follow the finger of your right hand. Move the wire one turn in or towards the direction of the magnetic field and a current will flow in the wire. The direction of the current depends on the direction of motion. Maxwell’s theory contradicted Newtonian mechanics, but experiments proved Maxwell’s equations. Einstein’s special theory of relativity finally resolved this contradiction.
There may seem to be few surprises in classical electromagnetic theory, but one aspect of what is generally considered “right” is wrong, according to the two researchers. They theorize that a device that sits passively on the Earth’s surface could generate electrical currents by interacting with the Earth’s magnetic field. The electrical power produced by the device will be measured in nanowatts, but could in principle be scaled up.
Experiments a century ago showed that if any electromagnet with cylindrical symmetry rotates about its long axis, its magnetic field does not. There is a component in the Earth’s magnetic field that is symmetric about the axis of rotation, so according to this old principle, the axisymmetric component does not rotate. Any stationary object on the Earth’s surface sweeps across this magnetic field component, which is constant at any latitude. Another fundamental conclusion of electromagnetism is that no electric current can be induced in a conductor moving through a uniform magnetic field. Charges inside the material are subjected to lateral forces and can in principle generate an electric current. But the displacement of the electrons and nuclei soon creates an electrostatic field that opposes the magnetic force. A balance between the electromagnetic forces is quickly established, so there is no net movement of charge after the tiny initial rearrangement. Magnetism can generate electricity
This principle seems to negate the idea that a stationary device on the Earth’s surface could generate any electricity while the non-rotating part of the Earth’s magnetic field moves at a constant velocity. But Chris Chiba of Princeton University and Kevin Hand of the Jet Propulsion Laboratory in Pasadena, California, see a way forward. In order to generate a current in a conductor, they need to create a magnetic force on the electrons that cannot be completely canceled out by the electricity. In what they call a hole in the traditional impossibility argument, the theorists have shown that certain configurations of magnetic fields cannot be canceled by electricity; however, these configurations require special conditions. The researchers show that this magnetic field structure may exist within a conductive cylindrical shell made of a material with unusual magnetic properties.
First, they point out that the magnetic field inside such a shell placed on the Earth’s surface — say, perpendicular to the Earth’s surface — is much smaller than the magnetic field outside. As the object sweeps through the Earth’s magnetic field, it constantly fights against the Earth’s uniform magnetic field and twists it into some sort of non-uniform configuration that keeps the field suppressed in inner space. If the magnetic properties of the housing material prevent rapid deformation of the incident field, the field will never reach its resting state. Magnetism can generate electricity
Chyba and Hand argued that the generated magnetic force cannot be canceled out by the generated electric field. The research team showed that in this case, electric currents can flow on certain closed paths inside the cylindrical shell. The electrodes can draw on this power source — which Chyba and Hand demonstrated ultimately comes from the energy of the Earth’s rotation. To design their new device, Chyba and Hand needed a conductive material with this unusual magnetic response — a difficult combination.
As an example of such a material, they found a manganese-zinc ferrite called MN60, which had the right properties and which, as Chyba puts it, was “a terrible conductor, only ten times as conductive as seawater One.” The team predicted little power due in large part to the low conductivity. A cylinder 20 centimeters long and 2 centimeters wide can generate tens of microvolts of energy in tens of nanowatts. Chyba believes there may be ways to increase those numbers, but he stresses that the first order of business is an experimental test to show that the mechanism really works. Philip Hughes, a radio astronomer at the University of Michigan in Ann Arbor who studies the magnetohydrodynamics of celestial bodies, says Chyba and Hand’s mechanism is “based on the physics of sound,” but he’s less optimistic about the possibility of scaling up. Magnetism can generate electricity
A magnetic field by itself does not generate electricity. The changing magnetic field will. While the Earth’s magnetic field does change a little bit, it’s not enough to make a big difference. Another option is to move the sensor in a magnetic field. However, Earth’s magnetic field is fairly uniform over short distances, so the coils would need to move fast and far to generate much. This will consume more energy than it produces. At least under the existing conditions, Chyba and Hand’s mechanism is not feasible, and the earth’s own magnetic field is still unable to generate electricity.