Worked Examples
E&M is a subject where the formulas are short and the setup is everything. These examples are worked end to end, with the reasoning that chooses the method made explicit — because choosing between Gauss, Biot–Savart and Ampère is most of the skill.
- Choosing a Gaussian surface — three geometries, three answers, and the case where Gauss's law is true but useless
- Designing a Helmholtz pair — why the separation equals the radius, worked with real numbers
Related tools
The Biot–Savart field builder computes the fields in the second example numerically and checks them against the closed forms; the E&M field explorer lets you place charges for the first.