Replacement Pith Balls for Electroscope, 10-Pack Subcategory_Pressure and Gas Laws Manually-operated seismograph model that traces

Manually-operated seismograph model that traces shock waves onto a pulled paper strip

and 4-pole armature configurations on the same motor frame by swapping interchangeable enameled-copper armatures past a permanent bar magnet on a disc commutator

and single-celled organism structure for protist biology teaching

Plastic-bodied wave apparatus with eccentric discs that drive metal rods up and down as the handle turns

Replacement Pith Balls for Electroscope, 10-Pack Subcategory_Pressure and Gas Laws Manually-operated seismograph model that tracesSpare pack of ten low mass pith balls sized for the standard pith ball electroscope, supplying replacements when the originals lose loft or split during repeated charging cycles.