Demonstration Electroscope Capacity_50mL supplying a duplicate-value option for

supplying a duplicate-value option for paired-bench experiments on capacitor energy storage

sized for two-cell battery-pack circuits and the standard ray-box and panel-lamp apparatus

demonstrating how sound transmission weakens as the air is evacuated

Concave glass mirror at 75mm diameter and 150mm focal length on a ~3mm-thick blank

and raised-graduated for shatterproof bench use

Demonstration Electroscope Capacity_50mL supplying a duplicate-value option forLarge 150mm ring with charging ball and condenser plates on an insulated rod, sized so the leaf deflection stays visible from the back of the room during whole class electrostatics demos.