Spare 500g Iron Hooked Weight with Retractable Hook Subject_Astronomy Seven-junction copper-and-iron thermopile from four

Seven-junction copper-and-iron thermopile from four 130mm wires of each metal

bending measurably under heat as differential thermal expansion of the two bonded metals drives the visible curvature

Alternate-model 75mm double-convex glass lens at 300mm focal length

Document analysis kit teaches forensic investigation through ink chromatography

Spare 500g Iron Hooked Weight with Retractable Hook Subject_Astronomy Seven-junction copper-and-iron thermopile from fourCast iron 500g mass carries a retractable hook for suspension from spring scales, pulleys, or beams, serving as a replacement piece for gravitational and force measurement setups.