00:01
We're going to think about the magnetic field caused by an electron moving at a fairly high speed, 5 times 10 to the 6 meters per second, in an observation point directly head of the electron.
00:16
And some folks don't like to think of an electron by itself creating a magnetic field.
00:22
That is, they'd rather think about a stable current with many electrons in it.
00:30
But certainly we can look at the fundamental biots of art law, which is very similar to the kulom's law for creating an electric field.
00:43
So in the biotsavart law, the magnetic field is proportional to the charge and its velocity, but also involves a fundamental constant, but also involves, the cross product with the r.
01:10
And to recall what r is, it is the separation between the source and the observation point.
01:18
So in our diagram, little r hat, the unit direction of that separation, is directly in line with the velocity.
01:29
It's the unit vector that connects our source to our observation point...