佑信 發問時間: 科學其他:科學 · 8 年前

介電質插入電容器

在下面狀況中,當介電質插入電容器後說明其儲存的能量會有何改變?(a)電容器沒有接電池,(b)電容器有接電池。

1 個解答

評分
  • 天同
    Lv 7
    8 年前
    最佳解答

    I suppose the capacitor is initially charged.

    (a) The insertion of a piece of dielectric increases the capacitance. Because the capacitor is isolated, no charge would flow. The energy stored in the capacitor thus decreases, as in according to the formula: energy stored = (1/2).(Q^2/C), where Q is the charge stored and C is the capacitance.

    (b) Because the voltage across the capacitor is now fixed, the increase of capacitance leads to a flow of charge from the battery so that the charge stored is increased.

    Hence, the energy stored in the capacitor is now increased.

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