1) Measuring instrument 
A Coulombmeter is a tool for measuring the electrostatic charge of a material. A Coulombmeter is used in combination with a Faraday cup or a metal probe for taking charge measures of a material. A Nanocoulombmeter is a Coulombmeter that is capable of measuring electrostatic charge down to the accuracy of a fraction of a nanocoulomb (nC). Electrost...
instrument for measuring electric charge