magnetic field lines

(noun)

A graphical representation of the magnitude and the direction of a magnetic field.

Related Terms

Examples of magnetic field lines in the following topics:

  • Magnetic Field Lines

    • Magnetic field lines are useful for visually representing the strength and direction of the magnetic field.
    • You can "connect" the arrows to form magnetic field lines.
    • For example, iron filings placed in a magnetic field line up to form lines that correspond to "field lines. " Magnetic fields' lines are also visually displayed in polar auroras, in which plasma particle dipole interactions create visible streaks of light that line up with the local direction of Earth's magnetic field.
    • If magnetic monopoles existed, then magnetic field lines would begin and end on them.
    • Relate the strength of the magnetic field with the density of the magnetic field lines

  • Helical Motion

    • shows how electrons not moving perpendicular to magnetic field lines follow the field lines.
    • Charged particles approaching magnetic field lines may get trapped in spiral orbits about the lines rather than crossing them, as seen above.
    • Those particles that approach middle latitudes must cross magnetic field lines, and many are prevented from penetrating the atmosphere.
    • When a charged particle moves along a magnetic field line into a region where the field becomes stronger, the particle experiences a force that reduces the component of velocity parallel to the field.
    • This force slows the motion along the field line and here reverses it, forming a "magnetic mirror. "

  • Electric vs. Magnetic Forces

    • The angle dependence of the magnetic field also causes charged particles to move perpendicular to the magnetic field lines in a circular or helical fashion, while a particle in an electric field will move in a straight line along an electric field line.
    • There are some notable differences between how electric and magnetic field lines are conceptualized.
    • The electric field is directed tangent to the field lines.
    • In the case of magnets, field lines are generated on the north pole (+) and terminate on the south pole (-) - see the below figure.
    • The magnetic pole model: two opposing poles, North (+) and South (−), separated by a distance d produce an H-field (lines).

  • Constant Velocity Produces a Straight-Line

    • If a charged particle's velocity is parallel to the magnetic field, there is no net force and the particle moves in a straight line.
    • The force a charged particle "feels" due to a magnetic field is dependent on the angle between the velocity vector and the magnetic field vector B .
    • In this case a charged particle can continue with straight-line motion even in a strong magnetic field.
    • In the case above the magnetic force is zero because the velocity is parallel to the magnetic field lines.
    • Identify conditions required for the particle to move in a straight line in the magnetic field

  • Induced EMF and Magnetic Flux

    • It is the change in magnetic field that creates the current.
    • The magnetic flux through some surface is proportional to the number of field lines passing through that surface.
    • where B is the magnitude of the magnetic field (having the unit of Tesla, T), A is the area of the surface, and θ is the angle between the magnetic field lines and the normal (perpendicular) to A.
    • For a varying magnetic field, we first consider the magnetic flux $d\Phi _B$ through an infinitesimal area element dA, where we may consider the field to be constant:
    • Explain the relationship between the magnetic field and the electromotive force

  • Maxwell's Equations

    • Gauss's law for magnetism states that there are no "magnetic charges (or monopoles)" analogous to electric charges, and that magnetic fields are instead generated by magnetic dipoles.
    • Magnetic field lines form loops such that all field lines that go into an object leave it at some point.
    • Faraday's law describes how a time-varying magnetic field (or flux) induces an electric field.
    • Maxwell added a second source of magnetic fields in his correction: a changing electric field (or flux), which would induce a magnetic field even in the absence of an electrical current.
    • The field lines created by this magnetic dipole either form loops or extend infinitely.

  • Energy Stored in a Magnetic Field

    • When a conductor carries a current, a magnetic field surrounding the conductor is produced.
    • From Eq. 1, the energy stored in the magnetic field created by the solenoid is:
    • Therefore, the energy density $u_B = energy / volume$ of a magnetic field B is written as $u_B = \frac{B^2}{2\mu}$.
    • Magnetic field created by a solenoid (cross-sectional view) described using field lines.
    • Energy is "stored" in the magnetic field.

  • Energy in a Magnetic Field

    • Magnetic field stores energy.
    • Energy is needed to generate a magnetic field both to work against the electric field that a changing magnetic field creates and to change the magnetization of any material within the magnetic field.
    • Magnetic field created by a solenoid (cross-sectional view) described using field lines.
    • Energy is "stored" in the magnetic field.
    • Express the energy density of a magnetic field in a form of equation

  • Ferromagnets and Electromagnets

    • If the current disappears, the magnetic field is turned off.
    • An electric current flowing in a wire creates a magnetic field around the wire.
    • The magnetic field from all the turns of wire passes through the center of the coil creating a strong magnetic field there.
    • The side of the magnet from which the field lines emerge is defined as the north pole.The main advantage of an electromagnet over a permanent magnet is that the magnetic field can be rapidly manipulated over a wide range by controlling the amount of electric current; a continuous supply of electrical energy is required to maintain the field.
    • Current (I) through a wire produces a magnetic field (B).

  • Magnitude of the Magnetic Force

    • The magnetic force on a charged particle q moving in a magnetic field B with a velocity v (at angle θ to B) is $F=qvBsin(\theta )$.
    • Magnetic fields exert forces on moving charges, and so they exert forces on other magnets, all of which have moving charges.
    • The Earth's magnetic field on its surface is only about 5×10−5 T, or 0.5 G.
    • There are many field lines, and so the fingers represent them.
    • Magnetic fields exert forces on moving charges.