Personal tools

Magnetism and Eletromagnetism

Cornell University_060120A
[Cornell University]


- Magnetism

Magnetism is a physical phenomenon, a highly diverse discipline, closely related to magnets and magnetic fields, which are triggered by the movement of electrical charges. 

Every substance is made up of tiny units called atoms. Every atom has electrons, particles that carry an electrical charge. Electrons spin like a top, orbiting the nucleus, or core. Their movement generates an electric current and causes each electron to act like a tiny magnet.

In most substances, the same number of electrons spins in opposite directions, canceling out their magnetism. This is why materials such as cloth or paper are considered weakly magnetic. In substances such as iron, cobalt and nickel, most electrons spin in the same direction. This makes the atoms in these substances strongly magnetic, but they are not yet magnets.

To be magnetized, another strongly magnetic substance must enter the magnetic field of an existing magnet. A magnetic field is the area around a magnet that has a magnetic force. 

All magnets have a north pole and a south pole. Opposites attract each other, like poles repel each other. When you rub a piece of iron along a magnet, the north-seeking poles of the atoms in the iron line up in the same direction. The forces produced by the aligned atoms create a magnetic field. That piece of iron became a magnet. 

Some substances can be magnetized by an electric current. When current flows through the coil, a magnetic field is generated. However, once the current is turned off, the magnetic field around the coil disappears.


Please refer to Mass Lowell: Formula Sheet - Electricity and Magnetism for more details.


- Electromagnetism

Magnetism and electricity are two fundamental aspects of electromagnetism - the branch of physics that studies the electromagnetic force and deals with electricity and magnetism and their interactions. It is a phenomenon that describes the interaction between electric and magnetic fields. There are two kinds of electromagnetic force: those associated with static charges and those associated with moving charges. 

Electromagnetic phenomena can be better described by saying that there are two kinds of charges, like charges repel each other, and unlike charges attract each other. The charge carried by protons is called positive charge, and the charge carried by electrons is called negative charge.


- Electromagnetism and Electromagnetic Force

In physics, electromagnetism is the interaction between charged particles through electromagnetic fields. Electromagnetism is one of the four fundamental forces of nature. It is the dominant force in the interaction of atoms and molecules. Electromagnetism can be thought of as a combination of electrostatics and magnetism, two distinct but closely intertwined phenomena. 

Electromagnetic force occurs between any two charged particles, causing attraction between particles with opposite charges and repulsion between particles with the same charge, whereas magnetism is an interaction that occurs only between charged particles in relative motion . These two effects combine to create an electromagnetic field near a charged particle, which can accelerate other charged particles through the Lorentz force. At high energies, the weak and electromagnetic forces are unified into a single electroweak force. 

The electromagnetic force is responsible for many chemical and physical phenomena observed in everyday life. The electrostatic attraction between the nucleus and its electrons holds the atoms together. Electricity also allows different atoms to combine into molecules, including large molecules such as proteins that form the basis of life. At the same time, the magnetic interaction between the electron's spin magnetic moment and angular momentum magnetic moment also plays a role in chemical reactions; spin chemistry studies this relationship. 

Electromagnetism also plays a vital role in modern technology: the production, conversion, and distribution of electrical energy; the generation and detection of light, heat, and sound; fiber optics and wireless communications; sensors; computing; electrolysis; electroplating; and mechanical motors and Actuator.



 [More to come ...]


Document Actions