Double Concave Glass Lens, 50mm Diameter, 100mm Focal Length, 16.5mm Thick Subcategory_Alternative Energy and an 18mm attachment diameter

and an 18mm attachment diameter for pulling small weights in mechanical-advantage experiments

Hand-painted animal cell model reveals organelle structures

applying tension to material strips until failure for breaking-strain and tensile-strength measurement in materials-science work

Larger brass conductor cone on an insulated rod and base

Double Concave Glass Lens, 50mm Diameter, 100mm Focal Length, 16.5mm Thick Subcategory_Alternative Energy and an 18mm attachment diameterDouble concave glass lens at 50mm diameter and 100mm focal length, a thick 16. 5mm blank with optically true surfaces, the diverging curvature producing virtual upright images for refraction work.