V P 1 V P 2 , {\displaystyle {\frac {V_{P1}}{V_{P2}}},\;} V S 1 V S 2 , {\displaystyle {\frac {V_{S1}}{V_{S2}}},\;} V S 1 V P 2 , {\displaystyle {\frac {V_{S1}}{V_{P2}}},\;} V P 1 V S 2 {\displaystyle {\frac {V_{P1}}{V_{S2}}}\;}
