Question

A parallel plate condenser has plates of area $200{cm}^2$ and separation $0.05cm.$ The space between plates have been filled with a dielectric having $k=8$ and then charged to $300$ volts. The stored energy:

• A. $121.5\times {10}^{-6}J$
• B. $28\times {10}^{-6}J$
• C. $112.4\times {10}^{-5}J$
• D. $1.6\times 64\times {10}^{-5}J$

Answer 1

The correct option is A $121.5\times {10}^{-6}J$

$C=\frac{KA{\in }_0}{d}=\frac{3\times 200\times {10}^{-4}\times 8.85\times {10}^{-12}}{5\times {10}^{-4}}$

$=27\times {10}^{-10}F$

$E=\frac{1}{2}C{V}^2=\frac{1}{2}\times 27\times {10}^{-10}\times 300$

$=\frac{243}{2}\times {10}^{-6}$

$=121.5\times {10}^{-6}J$

Hence,

option $\left(A\right)$ is correct answer.