Magnetism

Magnetism

is the class of physical attributes that occur through a magnetic field, which allows objects to attract or repel each other. Because both electric currents and magnetic moments of elementary particles give rise to a magnetic field, magnetism is one of two aspects of electromagnetism.

Ferromagnetic Materials

are familiar metals that are noticeably attracted to a magnet, the most common ones are iron, cobalt, and nickel and their alloys.

Ferromagnetism

is responsible for most of the effects of magnetism encountered in everyday life, but there are actually several types of magnetism

Paramagnetic

substances, such as aluminium and oxygen, are weakly attracted to an applied magnetic field

Diamagnetic

substances, such as copper and carbon, are weakly repelled

Antiferromagnetic

such as chromium, have a more complex relationship with a magnetic field

Nonmagnetic

The force of a magnet on paramagnetic, diamagnetic, and antiferromagnetic materials is usually too weak to be felt and can be detected only by laboratory instruments, so in everyday life, these substances are often described as

Magnetic Pole

region at each end of a magnet where the external magnetic field is strongest. A bar magnet suspended in Earth’s magnetic field orients itself in a north–south direction

North Magnetic Pole

The north-seeking pole of such a magnet is called a

South Magnetic Pole

The south-seeking pole, or any pole similar to it, is called a

Vector Field

Magnetic fields surround magnetized materials, electric currents, and electric fields varying in time. Since both strength and direction of a magnetic field may vary with location, it is described mathematically by a function assigning a vector to each point of space, called a

Magnetic Field

is a vector field that describes the magnetic influence on moving electric charges, electric currents and magnetic materials. A moving charge in a magnetic field experiences a force perpendicular to its own velocity and to the magnetic field

Magnetic Flux Density(B) and Magnetic Field Strength(H)

Two types of Vector Field

Tesla

Unit for Magnetic Flux Density

A/m

Unit for Magnetic Field Stength

Magnetic Flux Density

a measure of the strength of a magnetic field, also called magnetic induction

Magnetic Field Strength

is a measure of the intensity of a magnetic field, often represented by the symbol (H) and measured in amperes per meter (A/m)

Electromagnetic Waves

are made of oscillating electric and magnetic fields that are perpendicular to each other and to the direction of travel

Michael Faraday

English Scientist who discovered magnetic field

Electric Field

caused by stationary charges

Theory of Special Relativity

motion is relative, so a person moving with a line of charges, for example, wouldn’t perceive the magnetic field that a stationary person next to the moving charges would. This effect is fully explained by Einstein's theory in 1905

James Clerk Maxwell

Scottish Physicist who combined electricity and magnetism into a unified theory of magnetism in 1860s