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# 4: Magnetism

• 4.1: Magnetic Force
We begin our exploration of magnetism with a discussion of the effect that a magnetic field (the source and properties of which we will study later) has on electric charges.
• 4.2: Magnetic Moment and Torque
We extend our idea of an electric dipole into magnetism. Given there are no "point charges of magnetism," the idea of a magnetic dipole moment has even more utility than the electric dipole moment has.
• 4.3: Magnetic Field
Now that we know how magnetic fields exert forces on moving charges, we need to determine how to compute magnetic fields from their sources. As we did with electric fields, we will not only discuss a general procedure of integrating infinitesimal contributions, but will also catalog the fields for a few common geometries.
• 4.4: Sources of Magnetic Fields
Now that we know the basic cause of magnetic fields, we will practice calculating these fields, and will look at some common sources.
• 4.5: Ampère's Law
In electricity, we discussed the useful-if-abstract relationship between charge and field known as Gauss's law. As a close cousin to electricity, it should not be surprising that magnetism has a similar relationship between current and field. As we did with Gauss's law, we will find ways to use this mathematical relation to solve for fields of symmetric arrangements of field sources.