Question

A metal plate is given a positive charge . Then it's mass....

Answer 1

We can easily do this calculation. The capacitance of a sphere is:

C=4πε0r

and the charge is given by:

Q=CV=4πε0rV

The number of extra electrons is:

ne=Qe=4πε0rVe

And finally the mass of the extra electrons is:

M=mene=Qe=4πε0rVmee(1)

Let's take a copper sphere with a radius of 10cm charged to a million volts. If we put r=0.1m and V=106V into equation (1) we get: