Lessons In Electric Circuits, Volume 1, chapter 14: “Magnetism and Electromagnetism”
Lessons In Electric Circuits, Volume 1, chapter 15: “Inductors”
Lessons In Electric Circuits, Volume 2, chapter 3: “Reactance and Impedance—Inductive”
Wrap hundreds of turns of magnet wire around the paper tube. Connect this home-made inductor in series with an AC power supply and lamp to form a circuit. When the tube is empty, the lamp should glow brightly. When the steel bar is inserted in the tube, the lamp dims from increased inductance (L) and consequently increased inductive reactance (XL).
Try using bars of different materials, such as copper and stainless steel, if available. Not all metals have the same effect, due to differences in magnetic permeability.
by Jake Hertz
In Partnership with Rohde & Schwarz
by Steve Arar
In Partnership with EA Elektro-Automatik