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Electricity and magnetism are independent natural phenomena, but when they interact they generate a force called the electromagnetic force and constitute electromagnetism , a fundamental physics discipline in the study of various natural phenomena. Along with the gravitational force , electromagnetic forces explain the macroscopic phenomena of everyday life. They are responsible, for example, for the interactions between atoms to form molecules and compounds. Other fundamental forces of nature are the nuclear forces , the weak and the strong , which govern radioactive decay and the formation of atomic nuclei.
Electricity and magnetism are fundamental phenomena to understand the world around us; Let’s see below a basic description of each of them.
Electricity
Electricity is a phenomenon that originates from stationary or moving electric charges . These electric charges can be associated with an elementary particle, an electron (which has a negative charge), a proton (which has a positive charge), an ion or any body that has an imbalance of positive and negative charges, having thus a net electric charge. Positive and negative charges attract each other (for example, protons are attracted to electrons), while charges of the same sign repel each other (for example, protons repel other protons and electrons repel other electrons).
Examples of electricity that we can find in our daily lives are lightning that occurs during a storm, electrical current from a socket or battery, and static electricity. The units of the main parameters related to electricity, defined by the international system of SI units, are the ampere ( A ) for electric current, the coulomb ( C ) for electric charge, the volt ( V ) for the difference of potential, the ohm or ohm ( Ω ) for electrical resistance, and the watt ( W ) for power. A stationary point charge generates an electric field, but if the charge is in motion it also generates a magnetic field.
The magnetism
Magnetism is defined as the physical phenomenon produced by the movement of an electric charge. On the other hand, a magnetic field can induce the movement of charged particles by generating an electric current. An electromagnetic wave (like light, for example) has an electric field component and a magnetic field component. Electromagnetic waves are transverse waves; the two components of the wave travel in the same direction but their electrical and magnetic components are oriented perpendicular to the direction of the wave, and also perpendicular to each other.
Like electricity, magnetism produces attraction and repulsion between objects. Although electrical phenomena are based on the existence of positive and negative charges, magnetic monopoles are not known. The magnetic field generated by any particle or object has two poles of attraction, one called the north pole and the other called the south pole, assimilating them to the orientation of the Earth’s magnetic field. Like poles of a magnetic field generated by a magnet repel each other (for example, the north pole repels the north pole), while opposite poles attract each other (the north pole and the south pole attract each other).
Some familiar examples of magnetism are the alignment of a compass needle with Earth’s magnetic field, the attraction and repulsion of magnets, and the field observed around an electromagnet. Each electric charge in movement generates a magnetic field, so the electrons of the atoms when orbiting around the nucleus generate a magnetic field. The displacement of electrons associated with an electric current also generates magnetic fields around conducting wires. Computer data storage hard drives and loudspeakers also use magnetic fields to operate. The units of some of the main parameters related to magnetism, defined by the international system of SI units, are the tesla ( T) for magnetic flux density, the Weber ( Wb ) for magnetic flux, and the Henry ( H ) for inductance.
electromagnetism
The word electromagnetism comes from a combination of the Greek words elektron , which means amber, and magnetis lithos , which means magnesium stone, which is a magnetic iron ore. In ancient Greece they were familiar with electricity and magnetism, but considered them separate phenomena.
The theoretical bases of electromagnetism were exposed by James Clerk Maxwell in the book A Treatise on Electricity and Magnetism .) published in 1873. In the treatise Maxwell exposed the mathematical structure of electromagnetism in twenty equations, condensed into four equations with partial derivatives. Maxwell’s theory was supported by experimental evidence. Regarding electric charges, he observed that like charges repel each other and unlike electric charges attract each other; The force of attraction or repulsion between electric charges is inversely proportional to the square of the distance between them. Regarding the magnetic poles, they always exist as north-south pairs; Like poles repel each other and unlike poles attract.
The experimental evidence that supported Maxwell’s theory of the relationship between electricity and magnetism has two elements. A first observation establishes that an electric current circulating in a conductor generates a magnetic field around the cable. The direction of the magnetic field, clockwise to counterclockwise, depends on the direction of the current. This can be determined with the right hand rule; By ideally wrapping your right hand around the wire by putting your thumb in the direction of the current, the direction of the magnetic field follows the direction of your other fingers. On the other hand, the movement of a closed electrical conductor in the form of a loop or loop in a magnetic field induces an electrical current in the wire. The direction of the current depends on the direction of movement.
Sources
- Hunt, Bruce J. (2005). The Maxewllians . Cornell: Cornell University Press. pages 165 and 166. ISBN 978-0-8014-8234-2.
- International Union of Pure and Applied Chemistry (1993). Quantities, Units and Symbols in Physical Chemistry , Second Edition, Oxford: Blackwell Science. ISBN 0-632-03583-8. pages 14 and 15.
- Ravaioli, Fawwaz T. Ulaby, Eric Michielssen, Umberto (2010). Fundamentals of applied electromagnetics (sixth edition). Boston: Prentice Hall. page 13. ISBN 978-0-13-213931-1.
