length expansion

Previously, when interpreting a straight wire as a theory of length contraction, we looked at some problems. Below is a link to my last post. Today we will look at the circular wire. Origin of magnetic force   It is well known that electric and magnetic forces are the same force. But it is still not easy to qualitatively understand it. Today's magnetic force is interpreted as the 'relativistic effect of moving charge'. This field was pioneered by Purcell. When I talked about the last straight wire, I had a little explanation, but let's take a look at it again. Figure 1. Movement of charge from the lab point of view The test charge moves to the speed of v to the right, and the negative charge moves to the speed of v o to the right. From the point of view of the test charge, it is as follows. Figure 2. The movement of charge from the viewpoint of the test charge From the test charge's point of view, it is Purcell's calculation...