Electromagnetic Levitation as a Demonstration and Lab Project

Electromagnetic levitation of small objects provides an ideal medium to illustrate several important physics principles related to electricity, magnetism, and circuits. Additionally, it provides a visually striking demonstration. As a demonstration, electromagnetic levitation is suitable for illustrating a range of topics including Earnshaw's theorem, force balance, electromagnets, circuits, feedback, and Newton's laws for rotation. Electromagnetic levitation also makes a suitable advanced lab or circuits project for undergraduate students. The setup I will be presenting consists of an electromagnet below which a small iron object is suspended. The position of the object is kept stable via a feedback loop consisting of an LED and photodiode pair that monitors the position of the iron object and then adjusts the current through the electromagnet accordingly. A synchronous detection system further provides a high degree of noise immunity, promoting advanced lab skills when used as a student project.