▁ ▁In ▁some ▁special ▁limit ing ▁cases , ▁for ▁example ▁in ▁the ▁ ▁weak - cou pling ▁B CS ▁theory ▁of ▁is otrop ic ▁s - wave ▁super con duct or ▁it ▁is ▁related ▁to ▁characteristic ▁Cooper ▁pair ▁size : ▁▁▁▁ ▁where ▁ ▁is ▁the ▁reduced ▁Plan ck ▁constant , ▁ ▁is ▁the ▁mass ▁of ▁a ▁Cooper ▁pair ▁( tw ice ▁the ▁electron ▁mass ), ▁ ▁is ▁the ▁F erm i ▁velocity , ▁and ▁ ▁is ▁the ▁super con duct ing ▁energy ▁gap . ▁ ▁The ▁ratio ▁, ▁where ▁ ▁is ▁the ▁London ▁pen etr ation ▁depth , ▁is ▁known ▁as ▁the ▁G in zburg – Land au ▁parameter . ▁Type - I ▁super con duct ors ▁are ▁those ▁with ▁, ▁and ▁type - II ▁super con duct ors ▁are ▁those ▁with ▁. ▁ ▁In ▁strong - cou pling , ▁an is otrop ic ▁and ▁multi - component ▁theories ▁these ▁expressions ▁are ▁modified ▁. ▁ ▁See ▁also ▁▁ ▁G in zburg – Land au ▁theory ▁of ▁super con duct ivity ▁▁ ▁B CS ▁theory ▁of ▁super con duct ivity ▁▁ ▁London ▁pen etr ation ▁depth ▁ ▁References ▁ ▁Category : Super con duct ivity <0x0A> </s> ▁Jacob ▁Johann ▁Kö h ler ▁( 2 3 ▁November ▁ 1 6 9 8 ▁in ▁Nar va ▁– ▁ 1 7 5 7 ▁in ▁T all inn ) ▁was ▁an ▁Est onian ▁printer ▁who ▁published ▁the ▁first ▁Est onian - language ▁Bible ▁in ▁ 1 7 3 9 . ▁ ▁References ▁ ▁Category : 1 6 9