Proving the Absence of Length Contraction Perpendicular to Velocity

When teaching conceptual physics, students almost always ask why length contraction only occurs parallel to velocity and not perpendicular to it. That’s a meaty conceptual question and one that always leaves me looking for a convincing, non mathematical explanation. Earlier this semester, I finally found what I think is the best one I’ve ever heard […]

Matter & Interactions II, Week 7

This week, I was away at the winter AAPT meeting in Atlanta. Students began working on the experiments from chapter 17, which serve to introduce magnetic fields. I want to emphasize some really cool things about the mathematical expression for a particle’s magnetic field: This is really a single particle form of the Biot-Savart law. […]