Optically Worked Double Concave Glass Lens, 75mm Diameter, 300mm Focal Length Science at Home_Chemical Science 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

Hand-cranked cam turning against both a straight follower and a lever follower

5 N/m spring constant

one fitted with an exploder piston for momentum and action-reaction investigations

Optically Worked Double Concave Glass Lens, 75mm Diameter, 300mm Focal Length Science at Home_Chemical Science Four 153 x 76mm platesLong focal double concave glass lens at 75mm diameter and 300mm focal length, the moderate curvature spreading light gently for divergence and virtual image formation work in refraction demos.