There are two identical capacitors, the first one is uncharged and ...

There are two identical capacitors, the first one is uncharged and filled with a dielectric of constant \( K \)
\( \mathrm{P} \) while the other one is charged to potential \( V \) having air between its plates. If two capacitors are joined end to end, the common potential will be
(1) \( \frac{V}{K-1} \)
(2) \( \frac{K V}{K+1} \)
(3) \( \frac{K V}{K-1} \)
(4) \( \frac{V}{K+1} \)