Invisible lines. Wouldn't it be nice if we could see electric and magnetic fields? A spay can of magic paint. This paint would color the E field one color and the B field another. It would also shade the color to show direction. A spay can around an antenna would be most interesting. This would let us see if the fields are really there and if they act as Maxwells equations predicts. We dont have this paint yet, but ferro fluids is a step in the right direction. This fabulous fluid is cheap and easy to make. Keep it away from kids and animals, dont drink it. Notice the points. They crawl up the field lines. These points are orientated by individual magnetic moments in the magnet. Notice how easy and prone they are to rotate. Watch closely when the bar magnet gets thrown in the plastic bowl of ferro fluid. Notice how quickly it rotates and builds a spherical field. https://www.youtube.com/watch?v=kL8...UE&feature=iv&annotation_id=annotation_388872 By the way, ferro fluid follows a conductor just like a field line. The next video is better. It shows the physical process of powering a magnetic field line. In the first part of the video, showing one magnet....one magnetic moment. Notice closely as the field line is pulled in one side, then rotated one half turn and then pushed out the other end. Everything is reversed when you reverse the rotation. This is how a magnetic moment works. Notice that the in and out motion of the magnetic field line is perpendicular to the rotation. Notice also that it is the rotation that powers the magnetic line. https://www.youtube.com/watch?v=V-dbGUcnFaI&list=PLyJxyy34ZcGw5qJnYR29TTkeeQztwZJbN&index=19 Some are startled and surprised by some of these experiments. Maxwell's equations did not predict these processes and relationships. There was another man about one hundred years ago who experimented with circuits. His equations show that rotation and angular momentum is what controls the relationship between the electric and the magnetic. His name is Weber. This man set the standard for experimentation. Weber said that Amperes current elements(electrons) were very tiny rings of current. Each with it own magnetic moment. Over one hundred years ago. Genius.