Question1
We consider the cylinder as two cylindrical capacitors in parallel. The two “negative plates” are
the (connected) halves of the inner cylinder (half of which is in contact with liquid, and half of
which is in contact with vapor). The two “positive plates” are the (connected) halves of the
outer cylinder (half of which is in contact with liquid, and half of which is in contact with
vapor).
![{\displaystyle C=C_{\textrm {liq}}+C_{\textrm {V}}={\frac {2\pi \epsilon _{0}K_{\textrm {liq}}h}{\ln(R_{a}/R_{b})}}+{\frac {2\pi \epsilon _{0}K_{\textrm {V}}(l-h)}{\ln(R_{a}/R_{b})}}={\frac {2\pi \epsilon _{0}l}{\ln(R_{a}/R_{b})}}\left[(K_{\textrm {liq}}-K_{\textrm {V}}){\frac {h}{l}}+K_{\textrm {V}}\right]=C}](https://wikimedia.org/api/rest_v1/media/math/render/svg/5dd299e5b41123cf7d3b656767864a70cfa87966)
![{\displaystyle {\frac {h}{l}}={\frac {1}{(K_{\textrm {liq}}-K_{\textrm {V}})}}\left[{\frac {C\ln(R_{a}/R_{b})}{2\pi \epsilon _{0}l}}-K_{\textrm {V}}\right]}](https://wikimedia.org/api/rest_v1/media/math/render/svg/7eb2b5f4adaf00c6514371cf7cf812fc9df20558)
