Started with vector potential

    (pic) Demonstrated why 𝐉ᵦ = ∇×𝐌

(pic) Find magnetic field of a uniformly magnetized sphere

    this development ended up converging with the sphere of constant surface charge


(pic) Started with a reminder of displacement definition and origin.

    (pic) This leads to an analogy with 𝐉ₜₒₜ = 𝐉𝒻 + 𝐉ᵦ

    leads to very useful ∮𝐇⋅d𝐥 = 𝐈𝒻(s)

Bit of an aside about how 𝐇 is easier to measure/control compared to 𝐁.

(pic) An example of finding 𝐁 outside a thick rod.

    actually didn't develop this, but just warned about that M has a
    divergence at the edges, so 𝐇 is not so easy to find.

Introduced linear materials

    𝐌 = χₘ 𝐇

    χₘ > 0 (paramagnetic)

    χₘ < 0 (diamagnetic)

    Example: an infinite solenoid carrying a surface current 𝐊 = K ϕ̂ filled
    with material of susceptibility χₘ. Find 𝐁.

        (pic) found 𝐇, then 𝐁, then bound and free 𝐊