Premium Single D-Size Battery Holder with Curved Sides Physics_Alternative Energy Four 153 x 76mm plates

Four 153 x 76mm plates - each holding 98 iron-rod plotting compasses in a 14 x 7 matrix - assemble flat or as the faces of a cube to display 2D and 3D field-line patterns

Reproduces Oersted's 1820 experiment

expanding and closing to suit different optical-component sizes on a single bench-mounted holder

the shared mass isolating volume and density as the distinguishing variables across metals and polymers

Used to teach how AC/DC ammeters and voltmeters work

Premium Single D-Size Battery Holder with Curved Sides Physics_Alternative Energy Four 153 x 76mm platesCurved side single D cell holder in premium unbreakable plastic, sized so the heavier D cell stays seated when student built circuits are picked up, tilted, or carried between stations.