Several identical capacitors were connected in parallel and charged to a voltage `φ_(0)`. Subsequently they were reconnected in series with the aid of a switch. What will be the voltage across the terminals? Will the energy of the system change?

Explanation

The solution is obvious from Figs. 24.11a and 24.11b, which give the diagrams of the parallel and series connections of four identical capacitors. The energy in the case of parallel connection is
`W_("par")=(C_("par")Psi_("par")^(2))/(2)=(nC_(n)varphi_(0)^(2))/(2)`
and of series connections
`W_("ser")=(C_(ser) varphi_("ser")^(2))/(2)=((C_(0)//n)n^(2) varphi_(0)^(2))/(2)=W_("par")`