[*]This is called a potential because
electricity could flow between the two if they were shorted together, even
after the battery were removed. This charge is really an excess of electrons on
the backplate and an equivalent lack of electrons on the diaphragm.
[*]With an orchestra, you can zero in on the woodwinds, often
achieving a better balance on the recording than exists in the hall, were brass
and strings often dominate.