Concept Map

Concept Trailer

Key Terms

Ampere’s law

the physical law that states that the magnetic field around an electric current is proportional to the current; each segment of current produces a magnetic field like that of a long straight wire, and the total field of any shape current is the vector sum of the fields due to each segment

B-field

another term for magnetic field

Curie temperature

the temperature above which a ferromagnetic material cannot be magnetized

direction of magnetic field lines

the direction that the north end of a compass needle points

domains

regions within a material that behave like small bar magnets

electromagnet

an object that is temporarily magnetic when an electrical current is passed through it

electromagnetism

the use of electrical currents to induce magnetism

ferromagnetic

materials, such as iron, cobalt, nickel, and gadolinium, that exhibit strong magnetic effects

gauss

G, the unit of the magnetic field strength; 1 G=10–4T

Lorentz force

the force on a charge moving in a magnetic field

magnetic field

the representation of magnetic forces

magnetic field lines

the pictorial representation of the strength and the direction of a magnetic field

magnetic force

the force on a charge produced by its motion through a magnetic field; the Lorentz force

magnetic monopoles

an isolated magnetic pole; a south pole without a north pole, or vice versa (no magnetic monopole has ever been observed)

magnetic resonance imaging (MRI)

a medical imaging technique that uses magnetic fields create detailed images of internal tissues and organs

magnetized

to be turned into a magnet; to be induced to be magnetic

magnetocardiogram (MCG)

a recording of the heart’s magnetic field as it beats

magnetoencephalogram (MEG)

a measurement of the brain’s magnetic field

Maxwell’s equations

a set of four equations that describe electromagnetic phenomena

motor

loop of wire in a magnetic field; when current is passed through the loops, the magnetic field exerts torque on the loops, which rotates a shaft; electrical energy is converted to mechanical work in the process

north magnetic pole

the end or the side of a magnet that is attracted toward Earth’s geographic north pole

nuclear magnetic resonance (NMR)

solenoid

a thin wire wound into a coil that produces a magnetic field when an electric current is passed through it

south magnetic pole

the end or the side of a magnet that is attracted toward Earth’s geographic south pole

tesla

T, the SI unit of the magnetic field strength;

More terms can be found in the glossary, chapter 22.