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both removed, leaving A and Β well insulated, their charge and the
p.d. would remain. In practice one need not bother to distinguish
between
e.m.f.
and p.d. every time (Sec. 2.14). All that matters is the
voltage, and £and Κ do equally well.
As capacitance is equal to the charge required to set up a given
potential difference between two parts of a circuit or other objects,
one has to speak of the capacitance between those objects, or of one
to another.
3.3 Capacitance Analysed
We saw that when any object is being charged the current going into
it is greater than that coming out. So if Kirchhoff's law about
currents is true in all circumstances ...