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# Two capacitors $C_1$ and $C_2$ are charged to $120\: V$ and $200\: V$ respectively. It is found that by connecting them together the potential on each one can be made zero. Then:

$\begin {array} {1 1} (A)\;3C_1=5C_2 & \quad (B)\;4C_1 = 5C_2 \\ (C)\;5C_1 = 3C_2 & \quad (D)\;5C_1 = 4C_2 \end {array}$

If the potential can be made zero, then the only possibility is that the total charge
on them are equal In such a case, if opposite polarities are connected,
the potential across the two vanishes.
$\Rightarrow 120C_1 = 200C_2 \Rightarrow 3C_1 = 5C_2.$
This is a set of three similar question demonstrating a general technique to solve
any circuit with any level of complexity to obtain equivalent resistance.
Ans : (A)
edited Mar 14, 2014