Energy Tube, teaching resource for an array of scientific concepts: open and closed circuits, conductors vs. Insulators, light waves, sound waves,currents, and energy, When a conductor touches both of the electrodes on tube, tube emits a sound and flashing red/green/blue LED lights
Double Concave Optical round Lens, Material: Glass, designed for physics and educational uses, Because of their educational use design, there may be minor imperfections that do not affect physical function, Size: 250mm focal length, 50mm diameter and 3mm thick