. ▁In ▁the ▁situation ▁considered ▁here ▁the ▁volume ▁disp la ced ▁by ▁the ▁pro be ▁is ▁included ▁in ▁the ▁men is cus . ▁▁ ▁is ▁the ▁contact ▁angle ▁between ▁the ▁pro be ▁and ▁the ▁solution ▁that ▁is ▁measured , ▁and ▁is ▁neg lig ible ▁for ▁the ▁majority ▁of ▁solutions ▁with ▁K ib ron ’ s ▁prob es . ▁ ▁Thus , ▁the ▁force ▁measured ▁by ▁the ▁balance ▁is ▁given ▁by ▁ ▁where ▁▁ ▁is ▁the ▁force ▁acting ▁on ▁the ▁pro be ▁and ▁▁ ▁is ▁the ▁force ▁due ▁to ▁bu oy ancy . ▁ ▁At ▁the ▁point ▁of ▁det achment ▁the ▁volume ▁of ▁the ▁pro be ▁imm ers ed ▁in ▁the ▁solution ▁van ishes , ▁and ▁thus , ▁also ▁the ▁bu oy ancy ▁term . ▁This ▁is ▁observed ▁as ▁a ▁maximum ▁in ▁the ▁force ▁curve , ▁which ▁rel ates ▁to ▁the ▁surface ▁t ension ▁through ▁ ▁The ▁above ▁deriv ation ▁holds ▁for ▁ideal ▁conditions . ▁Non - ide al ities , ▁e . g . ▁from ▁defect ▁pro be ▁shape , ▁are ▁partly ▁compens ated ▁in ▁the ▁cal ibration ▁routine ▁using ▁a ▁solution ▁with ▁known ▁surface ▁t ension . ▁ ▁Adv antages ▁and ▁practice ▁ ▁Un like ▁a ▁du ▁No ü y ▁ring , ▁no ▁correction ▁factors ▁are ▁required ▁when ▁calculating ▁surface ▁t ensions . ▁ ▁Due ▁to ▁its ▁small ▁size ▁the ▁rod ▁can ▁be ▁used ▁in ▁high ▁through put ▁instruments ▁that ▁use ▁a ▁ 9 6 - well ▁plate ▁to ▁determine ▁the ▁surface ▁t ension . ▁ ▁The ▁small ▁diameter ▁of ▁the ▁rod