Tuesday, September 02, 2008

Review of SMT359 Electromagnetism

SMT359 is the Open University’s third-level undergraduate course on the classical theory of electromagnetism. Book 1 is a journey to Maxwell’s four equations, covering electrostatics (Gauss’s law), magnetism (the Biot-Savart and Lorentz force laws), Faraday’s law covering magnetic induction and the Ampere-Maxwell law covering magnetic fields due to currents and so-called ‘displacement currents’. There is also a hefty chapter on vector calculus for those who have forgotten their divs, grads and curls.

Book 2 puts the focus on electromagnetic fields. We spend a lot of time looking at electromagnetism in bulk materials (permittivity and permeability, D and H fields) and investigating the concepts of field potential and energy. The final two chapters take a detailed look at superconductivity in a classical context, and the unification of the electric and magnetic fields within special relativity (magnetism is a relativistic effect).

Book 3 is focused on electromagnetic waves. Maxwell’s equations may have resulted in the triumphal prediction of electromagnetic radiation, but it’s surprisingly hard to derive the specific equations for the radiation from an antenna. We then move on to consider dispersion and absorption of radiation in bulk materials. It turns out that mathematically this is the result of a complex (real + imaginary), frequency-dependent permittivity. The course closes by looking at plasma physics (think fusion reactors) and an essay on why the cornea of the eye is actually transparent.

SMT359 is a generally well-structured, solid, maybe even somewhat conservative course. It covers the core syllabus of introductory classical electromagnetism and doesn’t go substantially beyond it. Having now finished the units, I’m reading the Feynman Lectures in Physics, Volume II which address electromagnetism in a somewhat wider context and it’s pleasantly complementary.

In my opinion, this is not a course which can be skimmed. As you progress through it, it feels like a vast jigsaw puzzle – a lot of stuff has to be understood and be in your head before it has a chance to gel. I think, however, this is inherent in the structural complexity of classical electromagnetism.

I would have welcomed somewhere in the course a little peek ahead into what is covered both in more advanced treatments of classical electromagnetism, and in how Maxwell’s equations emerge as a limiting case from the quantum theory of electrodynamics. Perhaps a session on this might work at the summer school, SMXR359 ( which, by the way, it’s essential to attend to really anchor the concepts). Overall, SMT359 is an excellent course.