Rhythmic Ferrofluid: an iridescent magnetic fluid interacts with a variable strength electromagnet (like those found in speakers). A circuit supplies power to the electromagnet in proportion to the sound waves picked up by a microphone, the changing magnetic field- combined with the liquid surface tension of the colloidal ferromagnetic liquid- produces the captivating motion that keeps time with any music played. ➡️ Follow the link in my @physicsfun profile for info on where to get this device a