Using the charged ring potential we derive the potential and field for a homogeneously charged disk. Limiting cases and generalizations are discussed.

The quadrupole moments of a homogeneously charged ellipsoid are calculated. The result will help us to understand how and why the quadrupole moments of an ellipsoidal charge distribution changes if it gets into an excited state.

We will calculate the first three multipole moments of a deformed charged sphere. Such a charge distribution is often used to model nuclei and understand their stability.

The magnetic field of a thin and infinitely long wire is calculated using Biot-Savart's law.

Starting from specific examples, we find the general form of the multipole moments for charge distributions with rotational symmetry.

We calculate the magnetic field of a wire with constant current. Using symmetries we verify the right-hand rule.

The magnetic field for a current distribution in form of a cylinder shell is determined.