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Electric Current

Problem 3.201

A glass plate totally fills up the gap between the electrodes of a parallel-plate capacitor whose capacitance in the absence of that glass plate is equal to \(C=20 \mathrm{nF}\). The capacitor is connected to a dc voltage source \(V=100 \mathrm{~V}\). The plate is slowly, and without friction, extracted from the gap. Find the capacitor energy increment and the mechanical work performed in the process of plate extraction.

Reveal Answer
3.201.ΔW=−1/2(ε−1)CV2=−0.5 mJ,Amech ==1/2(ε−1)CV2=0.5 mJ\begin{aligned} & & 3.201 . \Delta W=-1 / 2(\varepsilon-1) C V^{2}=-0.5 \mathrm{~mJ}, & & A_{\text {mech }}=\\ =& 1 / 2(\varepsilon-1) C V^{2}=0.5 \mathrm{~mJ} \end{aligned}
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