Two-Way Copper Plug Key Switch with 4mm Terminals Plastic Labware_Plastic Measuring Cylinders and gauze-fronted object and receiving

and gauze-fronted object and receiving screens form this 1

where colored liquid in a U-shaped section shifts measurably as air blown through a constricted glass tube creates pressure differences

this acrylic light guide traps an injected ray-box beam by total internal reflection

hand-painted detail for blood-flow teaching

lock-screw

Two-Way Copper Plug Key Switch with 4mm Terminals Plastic Labware_Plastic Measuring Cylinders and gauze-fronted object and receivingTwo position copper plug key switch with 4mm terminals and two removable plugs, letting students route current down either branch of a circuit by choosing which slot the plug occupies.