Question

The capacitance of A conductor is affected by the presence of A second conductor that is uncharged and isolated electrically. Why?

Answer 1

What happens is the potential value of the conductor decreases due to the presence of second conductor
as the capacitance is given by C = q/v
the value of v deceases as v-v1
thus the new capacitance is = C' = q/v-v1 thus the lowering of v increases the capacitance