English: Drawing of a Kolbe electrometer, a precision type of gold-leaf electroscope. It has a light aluminum vane suspended next to a vertical metal plate (l). When an electric charge is applied to the electrode on the top of the instrument it flows down the vertical post, into the vane and plate. Since they have the same charge, the vane is repelled and hangs at an angle. From the angle read off the quadrant scale, the charge can be calculated.