Question

Two capacitors of capacitance $3\mu F$ and $6\mu F$ are charged to a potential of $12V$ each. They are now connected to each other, with the positive plate of each joined to the negative plate of the other. The potential difference across each will be :

• A. $4V$
• B. $12V$
• C. Zero
• D. $3V$

Answer 1

The correct option is B $12V$

Given, $C_1=3\mu F,C_2=6\mu F,V_1=V_2=12V$
$V=?$
The common potential across capacitors is given by
$V=\frac{C_1{V}_1+C_2{V}_2}{C_1+C_2}$
$V=\frac{3\times {10}^{-6}\times 12+6\times {10}^{-6}\times 12}{(3+6)\times {10}^{-6}}=12V$.