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
- 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; [latex]\text{1 G} = \text{10}^{–4} T[/latex]
- 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, [latex]\epsilon = \text{Blv}[/latex]
- 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 [latex]B = \frac{\mu_{0} I}{2 πr}[/latex], where [latex]I[/latex] is the current, [latex]r[/latex] is the shortest distance to the wire, and [latex]\mu_{0}[/latex] is the permeability of free space
- magnetic field strength at the center of a circular loop
- defined as [latex]B = \frac{\mu_{0} I}{2 R}[/latex] where [latex]R[/latex] is the radius of the loop
- magnetic field strength inside a solenoid
- defined as [latex]B = \mu_{0} \text{nI}[/latex] where [latex]n[/latex] is the number of loops per unit length of the solenoid [latex]\left(\right. n = N / l[/latex], with [latex]N[/latex] being the number of loops and [latex]l[/latex] the length)
- 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
- 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 [latex]I[/latex] and not [latex]\theta[/latex], 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 [latex]\mu_{0} = 4π \times \text{10}^{- 7} T \cdot \text{m}/\text{A}[/latex]
- 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 [latex]\textbf{v}[/latex] and the fingers point in the direction of the magnetic field [latex]\textbf{B}[/latex], 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; [latex]\text{1 T} = \frac{\text{1 N}}{A \cdot m}[/latex]
“Glossary” from College Physics 2e by OpenStax is licensed under a Creative Commons Attribution 4.0 International License.
