Stumblios

I read this article, and then down into the comments, stopping when someone quoted from a FAQ somewhere. Well, with an answer like this, I guess “frequently” is a relative term. Almost as fun as the airplane on a conveyor belt, but not quite.

“Q. Why does the net force not get balanced out by the axial component of the sidewall force? A. The net force is not balanced out by the axial component of the sidewall force because there is a highly non linear relationship between waveguide diameter and group velocity. (e.g. at cut off diameter, the group velocity is zero, the guide wavelength is infinity, but the diameter is clearly not zero.) The design of the cavity is such that the ratio of end wall forces is maximised, whilst the axial component of the sidewall force is reduced to a negligible value.”