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📚AP Physics C: E&M Unit 12 Vocabulary

55 essential vocabulary terms and definitions for Unit 12 – Magnetic Fields & Electromagnetism

Study Unit 12
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📚Unit 12 – Magnetic Fields & Electromagnetism
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📚Unit 12 – Magnetic Fields & Electromagnetism

12.1 Magnetic Fields

TermDefinition
bar magnetA permanent magnet with distinct north and south poles that produces closed-loop magnetic field lines.
diamagnetismA property of all materials in which their electronic structure creates a usually weak alignment of dipole moments opposite to an external magnetic field.
external magnetic fieldA magnetic field applied to a material from an outside source.
ferromagnetic materialsMaterials such as iron, nickel, and cobalt that can be permanently magnetized by an external field through alignment of magnetic domains or atomic magnetic dipoles.
free spaceA region of space with no matter, having a constant magnetic permeability value.
Gauss's law for magnetismMaxwell's second equation stating that magnetic field lines form closed loops and there are no magnetic monopoles.
induced magnetismA system property resulting from the alignment of magnetic dipoles within a material caused by an external magnetic field.
magnetic dipoleA system with a north and south magnetic pole that results from the circular or rotational motion of electric charges, such as moving electrons in atoms.
magnetic domainsRegions within ferromagnetic materials where atomic magnetic dipoles are aligned in the same direction.
magnetic fieldA vector field that determines the magnetic force exerted on moving electric charges, electric currents, or magnetic materials.
magnetic field linesLines that represent the direction and strength of a magnetic field, forming closed loops that never begin or end.
magnetic forceThe force exerted on a moving charged particle or current-carrying conductor in the presence of a magnetic field.
magnetic monopoleA hypothetical isolated magnetic charge that does not exist in nature; magnetic fields are always produced by dipoles.
magnetic permeabilityA property of a material that describes how easily a magnetic field can be established within it; affects the inductance of a solenoid.
magnetic polesThe regions at the ends of a magnetic dipole where magnetic effects are strongest; poles of the same polarity repel while opposite poles attract.
magnetizationThe process by which a material becomes magnetized or the degree to which a material is magnetized in response to an external magnetic field.
Maxwell's equationsA collection of four fundamental equations that fully describe electromagnetism and the behavior of electric and magnetic fields.
north poleOne end of a magnetic dipole from which external magnetic field lines point away.
paramagnetic materialsMaterials such as aluminum, titanium, and magnesium that interact weakly with an external magnetic field and do not retain alignment after the field is removed.
permanent magnetismA system property resulting from the alignment of magnetic dipoles within a material that persists without an external magnetic field.
south poleOne end of a magnetic dipole to which external magnetic field lines return.
vacuum permeabilityThe constant value of magnetic permeability in free space, denoted as μ₀, that appears in equations representing physical relationships.
vector fieldA field in which each point in space is associated with a vector quantity, such as a magnetic field.
vector field mapA representation of a vector field showing the magnitude and direction of the field at various points in space.

12.2 Magnetism and Moving Charges

TermDefinition
charged objectAn object that possesses electric charge and can experience forces from electric and magnetic fields.
conductorA material that allows electric charge to move through it, with resistivity that typically increases with temperature.
cross-productA mathematical operation between two vectors that produces a third vector perpendicular to both, with magnitude equal to the product of their magnitudes and the sine of the angle between them.
Hall effectThe phenomenon where a potential difference is created across a conductor perpendicular to both the direction of current flow and an applied magnetic field.
Lorentz forceThe force exerted on a moving charged object by a magnetic field, given by F_B = q(v × B).
magnetic fieldA vector field that determines the magnetic force exerted on moving electric charges, electric currents, or magnetic materials.
moving charged objectAn object possessing electric charge that is in motion, producing a magnetic field in the surrounding space.
perpendicularAt a 90-degree angle; the magnetic field direction is perpendicular to both the velocity vector and position vector of a moving charged object.
position vectorA vector drawn from a moving charged object to a point in space, used to determine the direction and magnitude of the magnetic field at that point.
right-hand ruleA method for determining the direction of the magnetic field produced by a moving charged object by pointing the thumb in the direction of velocity and curling fingers to show the field direction.
velocityThe rate and direction of motion of an object.

12.3 Magnetic Fields of Current-Carrying Wires and the Biot-Savart Law

TermDefinition
Biot-Savart lawA fundamental law that defines the magnitude and direction of the magnetic field created by a small segment of electrical current.
circular loop of wireA wire bent into a circular shape through which current flows, creating a magnetic field with specific properties at its center.
concentric circlesCircles that share the same center point; the magnetic field lines around a current-carrying wire form concentric circles centered on the wire.
current-carrying wireA conductor through which electric current flows, creating a magnetic field in the surrounding space.
magnetic fieldA vector field that determines the magnetic force exerted on moving electric charges, electric currents, or magnetic materials.
magnetic field vectorsArrows representing the magnitude and direction of the magnetic field at specific points in space around a current-carrying wire.
magnetic forceThe force exerted on a moving charged particle or current-carrying conductor in the presence of a magnetic field.

12.4 Ampère's Law

TermDefinition
Ampère's lawA fundamental equation that relates the magnitude of the magnetic field to the electric current enclosed by a closed imaginary path.
Amperian loopA closed imaginary path drawn around a current-carrying conductor used to apply Ampère's law.
changing electric fieldA time-varying electric field that generates a magnetic field according to Maxwell's equations.
conductive cylinderA cylindrical conductor carrying current to which Ampère's law can be applied to determine the magnetic field.
current densityThe amount of electric current flowing per unit cross-sectional area of a conductor; a vector quantity.
current-carrying wireA conductor through which electric current flows, creating a magnetic field in the surrounding space.
electric currentThe flow of electric charge through a conductor, which generates a magnetic field.
magnetic fieldA vector field that determines the magnetic force exerted on moving electric charges, electric currents, or magnetic materials.
Maxwell's additionThe modification to Ampère's law stating that a changing electric field creates a magnetic field in addition to the magnetic field created by electric current.
Maxwell's equationsA collection of four fundamental equations that fully describe electromagnetism and the behavior of electric and magnetic fields.
moving charge carrierAn electric charge in motion that generates a magnetic field around it.
principle of superpositionThe principle that the total electric field is the vector sum of fields produced by individual charges.
solenoidA coil of wire wound in a tight, helical pattern that produces a uniform magnetic field when current flows through it.