Chapter 17, Problem 48P

To determine

The stored energy will be calculated.

Answer to Problem 48P

The answer is $2.3\times {10}^{3}J$ .

Explanation of Solution

Given data:

Capacitance, $C=4.2\times {10}^{-4}C$

Distance between plates, $d=1.5\times {10}^{-3}m$

Side of square plates, $8.0cm$

Formula used:

It is known that: $PE=\frac{Q^{2}d}{{\epsilon }_{0}A}$

Where,

  $PE$ is the potential energy or stored energy.

  $\text{Q}$ is the charge.

  $A$ is the area of the plate.

  $d$ is the distance between plates.

Calculation:

Applying the formula to calculate the stored energy, $PE=\frac{Q^{2}d}{{\epsilon }_{0}A}$

  $\therefore PE=\frac{{\left(4.2\times {10}^{-4}C\right)}^2\left(1.5\times {10}^{-3}m\right)}{\left(8.85\times {10}^{-12}{C}^2/N\cdot m^2\right){\left(8.0\times {10}^{-2}m\right)}^2}$

  $\therefore PE=2.3\times {10}^{3}J$

Conclusion: The stored energy is $2.3\times {10}^{3}J$ .