Electricity and Magnetism

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Electricity & Magnetism

Magnetism and electric current are closely linked and together comprise electromagnetism, one of the elemental forces of the universe.

Manipulating magnetic fields, for example, through the acceleration of magnets, can generate a usable electric current, as is actually the case in some types of generators.

And at the same time, by circulating an electric current through certain types of metals, they can be turned into electromagnets and made to attract certain metals or ferromagnetic materials.

This relationship is based on the atomic nature of materials, in which electrons (-) from the outermost orbit of the atom's nucleus (+) can be torn off or transferred. from one molecule to another, thus generating an electric flow (current) and polarizing the whole, that is, tilting the electric charge toward one side (negative pole) and leaving the other side with a lesser charge (positive pole).

Magnetism

When we talk about magnetism or magnetic energy, we are referring to one of the two components of electromagnetic radiation (along with electricity) that manifests itself through forces of attraction or repulsion between certain types of materials and a magnetic energy field (magnetic field).

Although all substances are affected by magnetism, not all are affected in the same way. Some materials, such as certain ferromagnetic metals (especially iron, nickel, cobalt, and their alloys) are particularly prone to it and can therefore constitute magnets.

Some of these can be of natural origin, while others are artificial, for example, as a result of the action of electricity on certain materials (electromagnets).

Most magnets are magnetic dipoles: they have a positive and a negative pole. Each of these poles exerts a force on other magnets, or ferromagnetic metals, within its range of action, according to a law that establishes that like poles repel each other, while opposite poles attract.

These dipoles can occur on a macroscopic scale—for example, on planet Earth there is a North Pole and a South Pole, each exerting a magnetic influence that enables compasses to function—or on a microscopic scale, for example, in the orientation of certain organic molecules due to the electrical charge of their atoms.

And these forces of magnetism play an important role among the elemental forces of nature.

There are thus diamagnetic (weakly magnetic), paramagnetic (moderately magnetic), and ferromagnetic (highly magnetic) materials.

History of Magnetism

Humans have known about magnetism since early times. Its effects were described in Greek antiquity by Thales of Miletus (625-545 BC) and other similar philosophers, who noticed that certain stones from the city of Magnesia on the Maeander (Asia Minor) attracted iron. This is where the name magnetism comes from.

Humans somehow managed to understand Earth's magnetism early on, using it in the manufacture of compasses around the 12th century, before the emergence of the sciences that would later devote themselves to the study of this phenomenon.

The first properly formal treatise on magnetism was written in the 13th century by the Frenchman Peter Peregrinus de Maricourt, a prelude to future scientific studies by William Gilbert (1600) and, above all, Hans Christian Orsted (1820), who discovered that magnetism was not limited solely to magnets, but was closely linked to electric current.

This opened the door for André-Marie Ampère, Carl Friedrich Gauss, Michael Faraday, and others to inaugurate the field of electromagnetism, and later for James Clerk Maxwell to define it through his famous set of equations.

Applications of Magnetism

Magnetism has been used by humanity for a long time. The invention of the compass and its use for orientation (marking the fixed direction of North on the planet) dates back hundreds of years and was key to the development of navigation and global exploration.

On the other hand, large magnets are used in the power generation industry, medicine (e.g., MRI scans), engineering (engine development, conduction and storage of electrical charges, etc.), and, above all, electronics.

Computing, for example, relies heavily on the use of magnetism to record information, combining it with electric current and knowledge of semiconductors.

Electricity

Electricity refers to a set of physical phenomena linked to the presence and transmission of electrical charges. There are several basic concepts that are closely related to electricity:

Electric charge: All known matter is made up of atoms that have an equal number of electrons (with a negative electrical charge) and protons (with a positive electrical charge). Atoms and molecules can be electrically charged, and this influences how they attract or repel each other and the configuration of the matter they form.

Electric current: Electrically charged particles, usually electrons, can flow through a conductive material, such as a wire. This transmission of electrical charges is called an electric current.

Electric fields: Electric fields produce work, measured in volts, on the particles that move within them. The electric potential at a point in space is the work that must be done per unit of charge to move that charge through an electric field from a reference point to the point in question.

Electric potential: Electric fields can perform various types of work, measured in volts. This is called electric potential.

The electrical properties of known materials depend on the configuration of the electrons in their atoms. Graphene, silver, and copper are currently the most powerful conductors of electrical energy available, while other materials such as glass, lucite, and mica are excellent insulators.

Although electricity has been known since ancient times, especially since the discovery of amber, a material that can be electrically charged, its formal study began in the 17th and 18th centuries, and it was only at the end of the 19th century that it became widely used industrially and domestically.

Origin of electricity

Electricity has always been present in the world. Primitive man could perceive it through visible phenomena such as lightning, or experience it through electric fish such as the Thunderfish of the Nile River, described by the ancient Egyptians.

Static electricity (which arises, for example, when rubbing an amber stick with wool or fur) was discovered by the ancient Greeks around 600 BC.

The first serious experiments with electricity took place around the 17th century. The field grew with the studies and contributions of Cavendish, Du Fray, van Musschenbroek, and Watson during the 18th century, and during the 19th century, a unifying theory of electricity and magnetism was developed: Maxwell's equations in 1865.

The generation of electricity as an industrial activity began almost at the beginning of the 20th century, after Morse demonstrated in 1833 how electricity could revolutionize the field of long-distance communications, and after the possibility of generating light using power lines, replacing gas lines, was proven.

Finally, the research of Tesla and Edison promoted electricity as a basic requirement for scientific and technological innovation within the framework of the Second Industrial Revolution.

Importance of electricity

Electricity is a versatile and transformative source, capable of being harnessed in different ways:

Generating light: Lamps and light bulbs allow us to harness the electric flow in a vacuum to radiate light, illuminating different environments and extending daylight hours beyond sunset.

Generating heat: The Joule effect describes how the passage of electrons through a conductor generates heat energy, which can be harnessed by resistors for heating, welding, or even cooking.

Generating movement: Various types of devices are activated by electricity to generate movement, such as motors and Rotors, which convert electrical energy into mechanical energy. On the other hand, electrical energy can be stored, for example, using batteries, and used when needed to generate movement, for example.

Transmitting data: Through electronic systems, electrical circuits, or wiring networks, electricity enables the activation of various types of components over vast distances.

Characteristics of electricity

Electricity consists of the transmission of electrons from the outermost layer of atoms (the furthest) to the next atom, flowing along the conductive material and altering certain of its properties along the way.

On the other hand, electricity is storable, which is why batteries were invented, capable of absorbing electric current and storing it in their chemical content, for later recovery.

Electric Current

Electric current is the movement of electric charges through a conductor. These charges are electrons, subatomic particles that orbit the atomic nucleus.

Electric currents are not harmless to the human body, which can withstand currents of up to around 16 amps. In other words, electricity can be dangerous. Brief, moderate contact with an electrical source can numb or numb muscles, while more serious contact can cause burns or even death.

Thanks to Nikola Tesla's studies, two forms of electrical current are known: direct current and alternating current (which varies cyclically in magnitude and direction).

Electromagnetism

Electromagnetism is the branch of physics that studies the relationships between electrical and magnetic phenomena, that is, the interactions between charged particles and electrical and magnetic fields.

In 1821, the fundamentals of electromagnetism were revealed through the scientific work of British scientist Michael Faraday, which gave rise to this discipline. In 1865, Scottish scientist James Clerk Maxwell formulated the four "Maxwell's equations," which fully describe electromagnetic phenomena.

Applications of Electromagnetism

Electromagnetic phenomena have very important applications in disciplines such as engineering, electronics, healthcare, aeronautics, and civil construction, among others. They appear in our daily lives, almost without us realizing it, in compasses, speakers, doorbells, magnetic cards, and hard drives.

What is electromagnetism used for?

Electromagnetism is very useful to humans as there are countless applications that meet their needs. Many instruments used daily function due to electromagnetic effects. The electric current that flows through all the outlets in a home, for example, provides multiple uses (the microwave oven, the fan, the blender, the television, the computer) that function due to electromagnetism.

Examples of Electromagnetism

The bell: It is a device capable of generating a sound signal when a switch is pressed. It works through an electromagnet that receives an electrical charge, which generates a magnetic field (a magnetic effect) that attracts a small hammer that impacts the metal surface and emits a sound.

The magnetic levitation train: Unlike the train driven by an electric locomotive that moves on rails, this is a means of transportation that is supported and propelled by the force of magnetism and the powerful electromagnets located at the bottom.

The electric transformer: It is an electrical device that allows the voltage (or tension) of an alternating current to be increased or decreased.

The electric motor: It is a device that converts electrical energy into mechanical energy, producing movement through the action of the magnetic fields generated within it.

The dynamo: It is an electrical generator that uses the mechanical energy of a rotary motion and transforms it into electrical energy.

The Microwave oven: It is an electric oven that generates electromagnetic radiation at microwave frequencies. This radiation causes the water molecules in food to vibrate, which rapidly produces heat and cooks the food.

Magnetic resonance imaging: It is a medical examination that obtains images of the structure and composition of an organism. It involves the interaction of a magnetic field created by a machine, the magnetic resonator (which works like a magnet), and the hydrogen atoms contained in the person's body. These atoms are attracted by the "magnetic effect" of the device and generate an electromagnetic field that is captured and represented in images.

Microphone: It is a device that detects acoustic energy (sound) and transforms it into electrical energy. It does this through a membrane (or diaphragm) that is attracted by a magnet within a magnetic field, producing an electric current proportional to the sound received.

Planet Earth: Our planet functions as a giant magnet due to the magnetic field generated in its core (made up of metals such as iron and nickel). The Earth's rotational motion generates a current of charged particles (the electrons in the atoms of the Earth's core). This current produces a magnetic field that extends several kilometers above the planet's surface and repels harmful solar radiation.

Activity. Answer the following questions.

Remember to review the answers in the open-ended sections at the bottom of this page.

1. What type of material is most likely to become a magnet?

2. What type of electric current varies cyclically in magnitude and direction?

3. What device converts electrical energy into mechanical energy?

4. What device converts mechanical energy into electrical energy?

Once you click this button, the answers will close and you won't be able to change your answer.

6. What happens when an electric current flows through certain metals?

7. What types of materials are particularly prone to magnetism?

8. How was magnetism used in ancient times for orientation?

9. What impact did Hans Christian Oersted's work have on the study of electromagnetism?

10. What is one of the main applications of magnetism in medicine?

Still have questions?

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Answers to open-ended questions:

6. By passing an electric current through certain types of metals, they can be transformed into electromagnets and caused to attract certain ferromagnetic metals or materials.

7. Some materials, such as certain ferromagnetic metals (especially iron, nickel, cobalt, and their alloys), are particularly prone to this and can therefore constitute magnets.

8. Humans gained an early understanding of Earth's magnetism, using it in the manufacture of compasses around the 12th century, before the emergence of the sciences that would later dedicate themselves to the study of this phenomenon.

9. Hans Christian Orsted discovered that magnetism was not limited solely to magnets, but was closely linked to electric current. This opened the door for André-Marie Ampère, Carl Friedrich Gauss, Michael Faraday, and others to inaugurate the field of electromagnetism.

10. Magnetism has been used by humanity in medicine, for example, in MRI examinations.

1. Leskow, E. C. (2024c, octubre 24). Magnetismo - Concepto, historia y aplicaciones. Concepto. https://concepto.de/magnetismo/

2. Leskow, E. C. (2024b, octubre 24). Electricidad - Concepto, origen, importancia y características. Concepto. https://concepto.de/electricidad-2/