コンデンサーの充電

$\displaystyle v$	$\textstyle =$	$\displaystyle \frac{q}{C}$	(22)
$\displaystyle vi$	$\textstyle =$	$\displaystyle \frac{q}{C}\frac{{dq}}{{dt}}$	(23)
$\displaystyle vi$	$\textstyle =$	$\displaystyle \frac{d}{{dt}}\left( {\frac{{q^2 }}{{2C}}} \right)$	(24)