MCQ
A parallel plate capacitor with a dielectric slab completely occupying the space between the  plates is charged by a battery and then disconnected. The slab is pulled out with a constant speed. Which of the following curves represent qualitatively the variation of the capacitance $C$ of the system with time?

  • B

  • C

  • D

Answer

Correct option: A.

a
${\rm{C}} = \frac{{{ \in _0}}}{{\rm{d}}}\left( {{\rm{A}} + \left( {{\rm{k}} - 1} \right)xl} \right)$

$ \Rightarrow {\rm{C}} = \frac{{{ \in _0}}}{{\rm{d}}}({\rm{a}} + ({\rm{k}} - 1)l({\rm{a}} - {\rm{vt}})$

$\Rightarrow$ linear

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