Capillary rise between parallel plates
= Capillary rise between parallel plates
{title2=$h=2\gamma\cos\theta/(\Delta\rho gd)$}
Two wide vertical plates separated by gap $d$ provide two contact lines per unit width. Upward surface-tension <force> $2\gamma\cos\theta$ balances column weight $\Delta\rho gdh$. Compared with a circular tube of radius $r$, the height ratio is $r/d$ for the same <fluid> and <contact angle>. Equal plate gap and tube diameter give half the tube rise.