Physics: An Introduction Chapter 22 -- Reference Tools and Resources

Chapter 22: Magnetism
Reference Tools and Resources

Reference Tools & Resources

I. Key Terms and Phrases

north pole: the north pole of a magnet is the end that tends to point northward with respect to the earth.

south pole: the south pole of a magnet is the end that tends to point southward wirh respect to the earth.

magnetic field: the field created by a magnetic material or a current.

magnetic field lines: a pictoral representation of a magnetic field.

tesla: the SI unit of the magnetic field.

magnetic force right-hand rule: the rule for determining the direction of the magnetic force on a moving charge or current. For a positive charge, place the fingers of you right hand along v so that they would curl toward B; your thumb then gives the direction of F. Reverse the direction for a negative charge.

magnetic field right-hand rule: the rule for determing the direction of the magnetic field created by a current. Orient the thumb of your right hand along the current, your fingers then curl in the direction of B.

Ampere's law: the fundamental law relating a current to the magnetic field it creates.

permeability of free space: the fundamental constant of magnetism in Ampere's law.

solenoid: an electrical device in which a wire has been wound into the geometry of a helix.

ferromagnetism: the phenomenon that some materials have regions of "permanent" magnetic fields created spontaneously.

paramagnetism: the phenomenon that some materials obtain a magnetic field after exposure to an external magnetic field.

diamagnetism: the phenomenon that matter produces a weak magnetic field in the opposite direction of an external magnetic field.

II. Important Equations

Name/Topic Equation Explanation
magnetic force on a moving charge F = qvBsin q The magnitude of the force on a moving charge in a magnetic field.

magnetic force on a current-carrying wire F = ILBsin q The magnitude of the magnetic force on a current-carrying wire.

electric currents and magnetic fields The magnitude of the magnetic field due to a long, straight current I.

two parallel, current-carrying wires The magnitude of the force between two parallel current-carrying wires.

solenoids The magnitude of the magnetic field inside a solenoid.

Name/Topic	Equation	Explanation
magnetic force on a moving charge	F = qvBsin q	The magnitude of the force on a moving charge in a magnetic field.
magnetic force on a current-carrying wire	F = ILBsin q	The magnitude of the magnetic force on a current-carrying wire.
electric currents and magnetic fields		The magnitude of the magnetic field due to a long, straight current I.
two parallel, current-carrying wires		The magnitude of the force between two parallel current-carrying wires.
solenoids		The magnitude of the magnetic field inside a solenoid.

III. Know Your Units

Quantity Dimension SI Unit
magnetic field (B) [M][A^-1][T^-2] T

permeability of free space (m₀) [M][L][A^-2][T^-2] T^.m/A

Quantity	Dimension	SI Unit
magnetic field (B)	[M][A^-1][T^-2]	T
permeability of free space (m₀)	[M][L][A^-2][T^-2]	T^.m/A