The loop consists of about 24 turns of copper wire, with the varnish scraped off in one part to provide a commutator. It is mounted on paper clip supports. With the loop "right side up" and current applies, the magnetic force causes the loop to rotate. With the loop "upside down" the insulation cuts the current, there is no magnetic force, and gravity causes it to rotate back down. With a little tinkering, it can be gotten to rotate quite rapidly.