Does anyone know of any good relativity labs for an
introductory course?
How about this:
1) Hold a magnet near the screen of a CRT. Observe that the "cathode rays"
(electrons) are deflected.
2) Analyze this in a frame comoving with the electrons. In this frame, the
electrons have velocity v=0. Therefore the magnetic force is
F = v cross B = 0
The electrons think they are being deflected by an *electric* field.
3) This is a good demonstration of relativity. In particular, there is a
very close correspondence between the following statements:
-- A spatial separation in one frame looks like
a time difference in another frame.
-- A magnetic field in one frame looks like
an electric field in another frame.
4) This qualitative experiment has a very low cost.
5) I'm not sure it's worth the effort, but maybe you could cobble up a
semi-quantitative version: Figure out the electron velocity. Set up a
magnetic field with known strength and geometry. Et cetera....