Glossary

Resource ID: 4CkselDB@4.4

Grade Range: PreK - 12

Sections

Glossary

Glossary

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

Biot-Savart law: a physical law that describes the magnetic field generated by an electric current in terms of a specific equation

direction of magnetic field lines: the direction that the north end of a compass needle points

gauss: G, the unit of the magnetic field strength; $1 G = 10^{–4} T$

Hall effect: the creation of voltage across a current-carrying conductor by a magnetic field

Hall emf: the electromotive force created by a current-carrying conductor by a magnetic field, $ε = Blv$

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 field strength (magnitude) produced by a long straight current-carrying wire: defined as $B = \frac{μ_{0} I}{2 πr},$ where $I$ is the current, $r$ is the shortest distance to the wire, and $μ_{0}$ is the permeability of free space

magnetic field strength at the center of a circular loop: defined as $B = \frac{μ_{0} I}{2 R}$ where $R$ is the radius of the loop

magnetic field strength inside a solenoid: defined as $B = μ_{0} nI$ where $n$ is the number of loops per unit length of the solenoid $(n = N / l,$ with $N$ being the number of loops and $l$ the length)

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

magnetic resonance imaging (MRI): a medical imaging technique that uses magnetic fields create detailed images of internal tissues and organs

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

meter: common application of magnetic torque on a current-carrying loop that is very similar in construction to a motor; by design, the torque is proportional to $I$ and not $θ,$ so the needle deflection is proportional to the current

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): a phenomenon in which an externally applied magnetic field interacts with the nuclei of certain atoms

permeability of free space: the measure of the ability of a material, in this case free space, to support a magnetic field; the constant $μ_{0} = 4π \times 10^{- 7} T \cdot m/A$

right-hand rule 1 (RHR-1): the rule to determine the direction of the magnetic force on a positive moving charge: when the thumb of the right-hand points in the direction of the charge’s velocity $v$ and the fingers point in the direction of the magnetic field $B,$ then the force on the charge is perpendicular and away from the palm; the force on a negative charge is perpendicular and into the palm

right-hand rule 2 (RHR-2): a rule to determine the direction of the magnetic field induced by a current-carrying wire: Point the thumb of the right-hand in the direction of current, and the fingers curl in the direction of the magnetic field loops

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; $1 T = \frac{1 N}{A \cdot m}$