Right hand rule for magnetic force on a moving particle.

The magnetic force is the flip-side of the electrostatic force. The magnetic force and electrostatic force are two sides of the same fundamental force, the electromagnetic, or Lorentz force, which acts on charged particles due to electromagnetic fields. While understanding electrostatic force is enormously important for the new MCAT, especially as an underpinning of chemistry. magnetism is a little different. Magnetic phenomena do not play the same kind of integral role as electrostatic force in determining the internal energy change of most chemical reactions, for example, but magnetism has a way of showing up in a multitude of contexts relevant to the exam such as the motion of a cleavage fragment in mass spectrometry, to the basis of diamagnetism in oxyhemoglobin, or why, for example, aromatic ring protons experience deshielding in 1H NMR.

WikiPremed Resources

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Magnetism Concept Cards
Chapter from the Wisebridge Learning System for Physics

Magnetism Practice Items
Problem set for Magnetism in PDF format

Magnetism Images
Image gallery for study with links to larger teaching JPEGs for classroom presentation

Question Drill for Magnetism
Conceptual Vocabulary Self-Test

Basic Terms Crossword Puzzle

Basic Puzzle Solution

Learning Goals

Proficiency

For a charged particle moving through a given magnetic field, be prepared to determine the magnitude and direction of the magnetic force.

Understand why particles moving through magnetic fields often follow circular or spiral trajectories.

Be able to determine the magnitude and direction of the force on a wire carrying current within an external magnetic field and understand how a torque may be produced on a current loop within a magnetic field.

Understand how to use the right hand rule for magnetic fields to determine the orientation of the magnetic field around a current carrying conductor.

Be able to predict the direction of the magnetic force operating between two parallel current carrying wires.

Understand what the magnetic field looks like within a solenoid.

Be able to distinguish diamagnetism, paramagnetism, and ferromagnetism.

Understand the concept of magnetic susceptibility and know how to interpret magnetization curves.

Suggested Assignments

Review the basic terms for magnetism using the question server. Complete the fundamental terms crossword puzzle. Here is the solution to the puzzle.

Study the physics cards for magnetism.

Perform the practice items for magnetism. Here is the answer key for the practice items.

In ExamKrackers Physics, read pp. 104-105. Perform practice items 89-96 on pg. 106.

Take a review tour of the magnetism web resources.

Conceptual Vocabulary for Magnetism

Magnetic field
Magnetic fields permeate space around electric currents, magnetic dipoles, and changing electric fields, exerting a magnetic force on moving electric charges and magnetic dipoles.
Magnetic dipole
A closed circulation of electric current creates a magnetic dipole.
Tesla
The tesla is the SI derived unit of magnetic field.
Ampère's circuital law
Ampère's circuital law relates the circulating magnetic field in a closed loop to the electric current passing through the loop.
Ferromagnetism
Ferromagnetism is defined as the phenomenon by which materials, such as iron, in an external magnetic field become magnetized and remain magnetized for a period after the material is no longer in the field.
Lorentz force
The Lorentz force is the force exerted on a charged particle in an electromagnetic field refering to the combined effects of any electric field and magnetic field.
Magnetic constant
The magnetic constant is equal to the vacuum permeability, also known as the permeability of free space.
Magnetic moment
The magnetic dipole moment is a measure of the strength of a magnetic source.
Paramagnetism
Paramagnetism is a form of magnetism which occurs only in the presence of an externally applied magnetic field, but unlike ferromagnetism, does not result in any retained magnetization.
Diamagnetism
Resulting from changes in the orbital motion of electrons, diamagnetism is a weak repulsion from a magnetic field only exhibited by a substance in the presence of an externally applied magnetic field.
Electromagnet
An electromagnet is a type of magnet in which the magnetic field is produced by the flow of an electric current.
Galvanometer
A galvanometer is an electromechanical transducer that produces a rotary deflection, through a limited arc, in response to electric current flowing through its coil.
Magnetostatics
Magnetostatics is the study of static magnetic fields.
Magnetization
Magnetization is a property of some materials that describes to what extent they are affected by magnetic fields and what magnetic field the material itself creates.
Cyclotron
A cyclotron is a type of particle accelerator in which a perpendicular magnetic field causes the particles to spiral almost in a circle so that they re-encounter the accelerating voltage many times.
Biot-Savart law
The Biot-Savart Law is an equation in electromagnetism that describes the magnetic field vector B in terms of the magnitude and direction of the source electric current, the distance from the current, and the magnetic permeability.
Permeability
Permeability is the degree of magnetization of a material that responds linearly to an applied magnetic field.
Curie point
The Curie point of a ferromagnetic material is the temperature above which it loses its characteristic ferromagnetic ability.
Saturation
Saturation is the state when the material cannot absorb a stronger magnetic field, such that an increase of magnetization force produces no significant change in magnetic flux density.
Remanence
Remanence is the magnetization left behind in a medium after an external magnetic field is removed.
Gauss
The gauss is the cgs unit of magnetic field.
Guiding center
The guiding center is a point around which the motion in a magnetic field of an electrically charged particle can be treated as the superposition of a relatively fast circular motion and a relatively slow drift of this point.
The gyroradius defines the radius of the circular motion of a charged particle in the presence of a uniform magnetic field.
Weiss domains
Weiss domains are small areas in a crystal structure of a ferromagnetic material with uniformly oriented magnetic momenta.
Coercivity
The coercivity of a ferromagnetic material is the intensity of the applied magnetic field required to reduce the magnetization of that material to zero after the magnetization of the sample has been driven to saturation.
Oersted
The oersted is the unit of magnetic field strength in the CGS electromagnetic system.
Electromagnetic shielding
Electromagnetic shielding is the process of limiting the flow of electromagnetic fields between two locations, by separating them with a barrier made of conductive material.
Dynamo theory
The dynamo theory proposes a mechanism by which a celestial body such as the Earth generates a magnetic field.
Geomagnetic reversal
A geomagnetic reversal is a change in the orientation of Earth's magnetic field such that the positions of magnetic north and magnetic south become interchanged.
Solenoidal vector field
A solenoidal vector field is a vector field with divergence zero.
Magnetic mirror
A magnetic mirror is a magnetic field configuration where the field strength changes when moving along a field line resulting in a tendency for charged particles to bounce back from the high field region.
Advanced terms that may appear in context in MCAT passages
Bohr magneton
The Bohr magneton is a physical constant of magnetic moment in atomic physics.
Antiferromagnetism
In materials that exhibit antiferromagnetism the spins of electrons align in a regular pattern with neighboring spins pointing in opposite directions.
Néel temperature
The Néel temperature is the temperature at which an antiferromagnetic material becomes paramagnetic.
Meissner effect
The Meissner effect is the expulsion of a magnetic field from a superconductor.
Superdiamagnetism
Superdiamagnetism is a phenomenon occurring in certain materials at low temperatures, characterised by the complete absence of magnetic permeability and the exclusion of the interior magnetic field.
Superparamagnetism
Superparamagnetism is a phenomenon by which magnetic materials may exhibit a behavior similar to paramagnetism even when at temperatures below the Curie or the Néel temperature.
Exchange bias
Exchange bias occurs in bilayers (or multilayers) of magnetic materials where the hard magnetization behavior of an antiferromagnetic thin film causes a shift in the soft magnetization curve of a ferromagnetic film.
Metamagnetism
Metamagnetism is a physical state of matter characterized by a superlinear increase of magnetization over a narrow range of applied magnetic field.
Spin glass
A spin glass is a disordered material exhibiting high magnetic frustration.
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