A parallel plate capacitor with width 4cm, length 8cm and separation between the plates of 4mm is connected to a battery of 20V. A dielectric slab of dielectric constant 5 having length 1cm, width 4cm and thickness 4mm is inserted between the plates of parallel plate capacitor. The electrostatic energy of this system will be ___________ $\in_{0} J .$

(Where $\in_{0}$ is the permittivity of free space)

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Vishal Baghel | Contributor-Level 10

2 months ago

$C_{e f f} = [\frac{ε_{0} (7 \times 4)}{4 / 10} + \frac{5 ε_{0} (1 \times 4)}{4 / 10}] \times 1 0^{- 2}$

$C_{e f f} = 1.2 ε_{0}$

Energy = $\frac{1}{2} C_{e f f} V^{2}$ $\frac{}{}_{}^{}$

$\frac{1}{2} (1.2 ε_{0}) (20) (20) = 240 ε_{0}$

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