Two identical metal plates are given positive charges \(\mathrm{Q}_{1}\) and
\(\mathrm{Q}_{2}\left(<\mathrm{Q}_{1}\right)\) respectively. If they are now
brought close to gather to form a parallel plate capacitor with capacitance
\(\mathrm{c}\), the potential difference between them is
(A) \(\left[\left(Q_{1}+Q_{2}\right) /(2 c)\right]\)
(B) \(\left[\left(\mathrm{Q}_{1}+\mathrm{Q}_{2}\right) / \mathrm{c}\right]\)
(C) \(\left[\left(\mathrm{Q}_{1}-\mathrm{Q}_{2}\right) /(2 \mathrm{c})\right]\)
(D) \(\left[\left(\mathrm{Q}_{1}-\mathrm{Q}_{2}\right) / \mathrm{c}\right]\)