A really small changeElectricity and Magnetism Level pending
Some systems are designed so that even the smallest changes that occur to them are magnified by their physical characteristic. Thus, these changes can be easily detected by our macroscopic instruments.
Estimate the radius (in S.I.) of a spherical conducting grain that would make the smallest possible change in the charge detectable to our voltmeter.
The precision rating of our voltmeter is \(1 mV\).