Glossary
Alignment (of Magnetic Dipoles in External Fields)
The tendency of magnetic dipoles within a material or a free dipole to orient themselves with the direction of an external magnetic field to minimize potential energy.
Example:
A compass needle demonstrates alignment by rotating to point along the Earth's magnetic field lines.
Circular or Rotational Motion of Electric Charges
The fundamental source of magnetic dipoles and, consequently, magnetic fields, such as electrons orbiting within atoms.
Example:
The circular or rotational motion of electric charges within the Earth's core is believed to generate its global magnetic field.
Closed Loops (Magnetic Fields)
A fundamental property of magnetic field lines, meaning they do not start or end at a single point but continuously loop back on themselves.
Example:
Unlike electric field lines, magnetic field lines around a bar magnet form closed loops, extending from the north pole, curving around to the south pole, and continuing through the magnet's interior.
Diamagnetic Materials
Materials that are weakly repelled by external magnetic fields, a property present in all materials due to their electronic structure.
Example:
Water and bismuth are diamagnetic materials; a strong enough magnet can cause them to levitate slightly.
Earth's Magnetic Field
A large-scale magnetic field generated by the motion of molten iron in the Earth's outer core, acting like a giant bar magnet and protecting the planet from solar radiation.
Example:
The Earth's magnetic field guides migratory birds and protects the atmosphere from solar winds.
Ferromagnetic Materials
Materials (like iron, nickel, cobalt) that can be strongly and permanently magnetized due to the alignment of their magnetic domains.
Example:
The core of an electromagnet is often made of ferromagnetic materials to concentrate the magnetic field.
Induced Magnetism
Temporary magnetism created in a material when it is placed within an external magnetic field, causing its dipoles to align with the field.
Example:
When you pick up a paperclip with a strong magnet, the paperclip temporarily gains induced magnetism.
Inverse-Square Relationship (Magnetic Field from Dipole)
Describes how the strength of the magnetic field produced by a dipole decreases proportionally to the square of the distance from the dipole.
Example:
The magnetic field from a small bar magnet weakens rapidly as you move away from it, following an inverse-square relationship.
Like Poles Repel
The principle that two north poles or two south poles of magnets will push each other away.
Example:
If you try to push the north pole of one magnet against the north pole of another, you'll feel them like poles repel.
Magnetic Dipoles
Objects or systems that have both a north and a south magnetic pole, created by the circular or rotational motion of electric charges.
Example:
A tiny current loop or an electron orbiting an atomic nucleus acts as a magnetic dipole.
Magnetic Field Lines
Imaginary lines used to visualize magnetic fields, whose density indicates field strength and whose direction indicates the field's orientation.
Example:
Sprinkling iron filings around a magnet reveals the pattern of its magnetic field lines.
Magnetic Fields
Vector fields that exert forces on moving charges, electric currents, and magnetic materials, acting as invisible force fields.
Example:
When a compass needle points north, it's aligning with the Earth's magnetic field.
Magnetic Monopoles
Hypothetical isolated north or south magnetic poles that do not exist in nature, unlike electric charges which can be isolated.
Example:
If you break a magnet in half, you don't get a separate north pole and a separate south pole; you get two smaller magnets, demonstrating the non-existence of magnetic monopoles.
Magnetic Permeability (μ)
A measure of how much a material will become magnetized in response to an external magnetic field, quantifying its 'magnetizability'.
Example:
Materials with high magnetic permeability are used in transformer cores to efficiently channel magnetic flux.
Opposite Poles Attract
The principle that a north pole and a south pole of magnets will pull towards each other.
Example:
A compass needle's north pole is drawn towards the Earth's magnetic south pole (near the geographic north pole) because opposite poles attract.
Paramagnetic Materials
Materials (like aluminum, titanium) that are weakly attracted to external magnetic fields, with their dipoles aligning temporarily but returning to random orientations when the field is removed.
Example:
Liquid oxygen is a paramagnetic material and can be weakly suspended between the poles of a strong magnet.
Permanent Magnetism
The property of certain materials to retain their magnetic properties even after an external magnetic field is removed, due to the alignment of their magnetic domains.
Example:
A refrigerator magnet exhibits permanent magnetism, sticking to the fridge door indefinitely.
Relative Permeability (μᵣ)
The ratio of a material's magnetic permeability to the vacuum permeability, indicating how much more or less permeable a material is compared to free space.
Example:
A material with a relative permeability of 1000 is 1000 times more permeable than a vacuum, making it excellent for magnetic shielding.
Vacuum Permeability (μ₀)
A fundamental physical constant representing the magnetic permeability of empty space, used in many electromagnetic equations.
Example:
The force between two current-carrying wires in a vacuum depends on the vacuum permeability.
Vector Field Maps
Visual representations that show magnetic fields as vectors, indicating both magnitude (strength) and direction at each point in space.
Example:
Engineers use vector field maps to design magnetic shielding, ensuring sensitive equipment is protected from external magnetic influences.
Vector Fields
Fields where every point in space is associated with a vector, indicating both magnitude and direction.
Example:
A weather map showing wind speed and direction at various locations is an example of a vector field.