The Magnetohydrodynamic Drive Is Real—and You Can Build One

January 27, 2018

The Magnetohydrodynamic Drive Is Real – & You Can Build One Great illustration of the cross product & the weird way #magnetism makes things curl around

“In the diagram, I have a magnet with the north side pointing down. This produces a magnetic field that also mostly points down (as indicated by the red arrow). Now for the awesome physics part. If you have an electric charge moving in a magnetic field, there is a force on that charge—the magnitude of this force depends on the strength of the magnetic field, the value of the electric charge, and the velocity of the charge. This magnetic force can be expressed as the following equation:

If don’t have a degree in physics, there are three things that are crazy about this equation. First, there is this weird arrow symbol over some of the variables. Nothing to be alarmed about—this just means these are vector quantities so that the direction also matters. Next there is this vector B. This represents the value of the magnetic field. Honestly, I’m not sure why we (physicists) always use B for the magnetic field—but we do. Lastly, there is that big “X”. That is not the sign for multiplication, that is the sign for the cross product. I guess I should also point out that “q” is the symbol for the electric charge.”