They are important industrially because they can be extremely high current generators. They are important to hobbyists and educators because there is no obvious reason why they turn at all. 
Most electric motors are designed to obviously have one electromagnet pushing on either another electromagnet, or a permanent magnet. The rotor of a homopolar motor never gets any closer or farther from permanent permanent magnet during it’s rotational cycle.
Please visit our homopolar motor kit page where you can download the complete instructions in the .pdf format and of course you can also buy one of our homopolar motor kits.