Greetings PF. I've got an idea for a demonstration of the speed of light utilizing a pulsed electromagnetic coil and ferrofluid. I'm concerned with the feasibility of this project as it may push the limits of semiconductor technology. I would appreciate any insight on the difficulties of this project since i'm not an electrical engineer. However, if it is feasible, i'll try to recruit some EEs to help me out. Here's how I expect it to work: When ferrofluid is placed on an electromagnet, the fluid is drawn to the magnetic field lines. With that in mind, I want to create a pulsed electromagnet where segments of the coil are energized and other aren't. This will result in the ferrofluid being attracted to the energized segments. The pulse duration will need to be about 1.2 nanoseconds with a coil diameter of 0.3m. calculation below: At 0.66c the speed of light (signal propagation in copper) is 197863022 m/s. With a 0.3m diameter coil and a 0.23m pulse wavelength, the oscilation rate comes down to ~1.2 ns pulse rate. The standard spiral coil which may make things difficult as more wire is required to make a revolution with the increasing radius. I wonder if there is a better winding geometry for this purpose. The wire on the coil will also need to be extremely small in diameter to allow for low current switching. I'm also concerned about rise/fall time and timing accuracy (I assume we'd use a crystal oscillator for a trigger). I'm sure there's a lot of issues I haven't thought of which is why i'm posting here. I appreciate any help you can provide.