A sphere with radius R=20mm is loaded till a potential V=-2KV. Find the weight of all electrons transferred to sphere, in the loading process.
The number of electrons and their weight:
We ahve to say it again that inside a sphere , the field and the potential are as the load would be concentrated in the center of sphere.
In particular, the potential of the sphere itself:
We'll draw out the load from this formula and we'll introduce it in (1):