Question

A 5 $\mu F$ capacitor is connected in series with a 10 $\mu F$capacitor. When a 300 V potential difference is applied across this combination, the total energy stored in the capacitors is:

• A. 15 J
• B. 1.5 J
• C. 0.15 J
• D. 0. 10 J

Answer 1

The correct option is C 0.15 J

.According to question the figure can be drawn as below (image)

The equivalent capacitance,

$\frac{1}{C_{eq}}=\frac{1}{C_1}+\frac{1}{C_2}=\frac{1}{5}+\frac{1}{10}$

$=\frac{2+1}{10}=\frac{3}{10}$

$\Rightarrow C_{eq}=\frac{10}{3}\mu F$

Now, the energy stored in the capacitor is

$U=\frac{1}{2}C{V}^2$

$=\frac{1}{2}\times \frac{10}{3}\times {10}^{-6}\times 300\times 300$

$=\frac{3}{10\times 2}=\frac{3}{20}=0.15J$